Neurodevelopment & Plasticity

Question 1

What are the five phases of neuron development?

Answer 1

• induction of the neural plate
• neural proliferation
• migration and aggregation
• axon growth and synapse formation
• neuron death and synapse rearrangement

Question 2

What happens during the induction of the neural plate?

Answer 2

• patch of tissue on the dorsal surface of the embryo becomes the neural plate
• development induced by chemical signals from the mesoderm
• visible three weeks after conception

Question 3

What happens during neural proliferation?

Answer 3

• neural plate folds to form the neural groove
• groove then fuses to form the neural tube
• swellings at the anterior end will become the forebrain, midbrain and hindbrain
• chemically guided by the organizer areas

Question 4

What happens during migration and aggregation?

Answer 4

-once cells have been created through cell division they migrate and group together

Question 5

What happens during axon growth and synapse formation?

Answer 5

-once migration is complete and structures have formed, axons and dendrites begin to grow

Question 6

What happens during neuron death and synapse and rearrangement?

Answer 6

• neurons die due to failure to compete for chemicals provided by targets
• death is normal, 50% more neurons are produced than needed

Question 7

What is anencephaly?

Answer 7

• infant born with a severely underdeveloped brain

- usually still have a brain stem, but do not have a forebrain or cerebrum

Question 8

What causes anencephaly?

Answer 8

the neural tube fails to close

Question 9

What are the two mechanisms of neural migration?

Answer 9

Somal & Glial

Question 10

What is somal migration?

Answer 10

an extension develops that leads migration, cell body follows

Question 11

What is glial migration?

Answer 11

cell moves along a radial glial network

Question 12

What is the chemoaffinity hypothesis?

Answer 12

• postsynaptic targets release a chemical that guides axonal growth
• does not explain the circuitous routes often observed

Question 13

What is necrosis?

Answer 13

passive cell death

Question 14

What is apoptosis?

Answer 14

• active cell death

- safer than necrosis because it does not promote inflammation

Question 15

What are neurotrophins?

Answer 15

• promote growth and survival
• guide axons
• stimulate synaptogenesis

Question 16

What is a critical period?

Answer 16

absolutely essential for an experience to occur within a particular time interval to influence development

Question 17

What is a sensitive period?

Answer 17

• an experience has great effect on development when it occurs during a particular time interval
• can still have weak effects outside the interval

Question 18

What are the consequences of early monocular deprivation?

Answer 18

• changes the pattern of synaptic input into V1

- altered exposure during a sensitive period leads to reorganization

Question 19

What happens to the axons from the lateral geniculate nucleus when monocular deprivation occurs?

Answer 19

-axons carrying information have less branches

Question 20

What is neurogenesis?

Answer 20

growth of new neurons

Question 21

Where does neurogenesis occur in adult mammals?

Answer 21

• hippocampus

- olfactory bulb