development

Question 0

how does the neural cord form?

Answer 0

groove in the neural plate forms
this deepens and the edges come together to form the neural cord underlying the ectoderm (breaks free of overlying ectoderm)

Question 1

which part of the laminar disc becomes the nervous system

Answer 1

part of the ectoderm

Question 2

what is the order of the closing neural tube down the embryo?

Answer 2

• first = exactly the middle - then zips upwards and downwards
• second = top of the head - zips backwards and forwards
• third = forehead from bottom to top
• fourth = nape of the neck
• fifth = bottom of the spine

Question 3

what are the two major congenital defects that are caused by an error in the fusion of the neural tube

Answer 3

ancephalopathy

spina bifida

Question 4

which end of the neural tube swells? and what are the 3 vesicles called

Answer 4

the rostral end

• prosencephalon
• mesencephalon
• rhombencephalon

Question 5

explain the further segmentation of the 3 vesicles of the neural tube?

Answer 5

prosencephalon - splits into telencephalon and diencephalon

rombencephalon splits into metencephalon and myeloencephalon –> 7 segments

Question 6

how are the retina formed

Answer 6

as optic vesicles from the diencephalon

Question 7

what does the diencephalon form in the adult human brain

Answer 7

thalamus and hypothalamus

Question 8

what does the telencephalon form in the adult human brain

Answer 8

cortex, basal ganglia and hippocampus

Question 9

what does the metencephalon form in the adult human brain

Answer 9

pons and cerebellum

Question 10

what does the myelencephalon form in the adult human brain

Answer 10

medulla

Question 11

what are the derivatives of the neural crest cells

Answer 11

• peripheral nervous system (DRG, sympathetic and parasympathetic ganglia, enteric ganglia and Schwann cells)
• melanocytes
• muscle, cartilage and bone of skull, jaws, face and pharynx
• dentine

Question 12

what is the direction of migration of neural crest cells

Answer 12

rostral to caudal - following specific paths

Question 13

where are the stem cells of the embryo brain

Answer 13

at the ventricular surface

Question 14

how does the cortex get its layers?

Answer 14

stem cells at the ventricular surface of the neural tube proliferate and are placed on the outside
further proliferation –> placed on the outside
(inside–> out building of the layers)

Question 15

what directs the proliferation of neural cells from the stem cells of the ventricular surface of the neural tube to its destination on the outside of the layers?

Answer 15

the radial glia

act as scaffolding to direct cells to the outer part of the cortex

Question 16

what are two major genes that influence migration of neural cells during the proliferation of the cortex? What do their deficiences cause?

Answer 16

Reelin - hardly any cells in the cortex (less white matter)

DCX - smooth surface (not convuluted)

Question 17

how does fragile X syndrome cause male autism

Answer 17

mutation of fragile X mental retardation gene –> affects synaptic and dendritic development

Question 18

what is the prime organiser of the spinal cord and how does it do this?

Answer 18

the notochord - it releases signals (eg sonic hedgehog) that affects the cells of the neural tube closest to it –> makes them become the floorplate

Question 19

what is the role of the floorplate in the induction of the spinal cord

Answer 19

it releases sonic hedgehog to induce the formation of the ventral horn motor neurons

Question 20

what do ventral motor neurons do in regards to development of the spinal cord

Answer 20

release motor neuron factor to induce interneurons just dorsal to the motor neurons

Question 21

how do axons grow?

Answer 21

the axons is towed into position by a growth cone which follows a gradient of diffusible and membrane bound signals

Question 22

what is the growth cone of axons made up of

Answer 22

actin and microtubules

Question 23

what does the refinement of the nervous system lead to

Answer 23

permanent changes that establish mature functional nervous system.
Refinements based on the early experiences of the nervous system - making and breaking connections

Question 24

what is the critical period for neural cortex plasticity

Answer 24

the amount of time you have for a certain refinement of a particular part of the cortex

Question 25

why dont you become blind in both eyes if you cover them both at birth?

Answer 25

because the plasticity of the neural cortex depends on the relative neural activity of both of the eyes (not absolute)