Brain Development

Question 1

What are the key elements in the process of brain development?

Answer 1

• Cell formation
• Cell migration
• Axon migration
• Connection formation

Question 2

Steps of the neural tube forms in the embryo?

Answer 2

• Flat section between the folds is the neural plate
• Folding around the neural plate produces the neural glove
• Groove closes up to create neural tube
• Central channel inside the tube develops into the cerebral ventricles and the spinal canal

Question 3

What two things need to happen for the formation of these structures?

Answer 3

• Cell division

- Cell migration

Question 4

Two types of neural tube migration

Answer 4

• Radial migration

- Tangential migration

Question 5

What is radial migration ?

Answer 5

Moves directly outwards from the central regions of the tube

Question 6

What is tangential migration?

Answer 6

Moves at right angles to radial paths

Question 7

Two methods of migration?

Answer 7

• somal: an extension develops that leads migration, cell body follows
• glial-mediated: Cell moves along a radial glial network

Question 8

What do radial glial cells develop into ?

Answer 8

Neurons

Question 9

What is axonal growth ?

Answer 9

The process in which the cells need to form the connections that are needed for them to work with each other

Question 10

What is filopodia?

Answer 10

As axons form their tip becomes a growth cone and develops finger-like antennae

Question 11

How do axons know where to connect?

Answer 11

• The filopodia feels for chemical signals in the environment which guides the axon along the route it needs to take
• Axons can also use signals from other axons along their route to guide them (known as fasciculation)

Question 12

What’s the hypothesis called for knowing that axons are capable of migrating precisely to their destinations?

Answer 12

Chemoaffinity hypothesis

Question 13

Why do axons need to grow ? How do they know where to go?

Answer 13

• So they can form connections that are needed for them to work with each other
• the filopodia feels for the chemical signals in the environment and guides the axon along the route it needs to take

Question 14

What happens to cells that are not correctly connected?

Answer 14

They are likely to die

Question 15

What are teratogens?

Answer 15

A factor which causes malformation of an embryo (risk factors)

Question 16

What theories have been suggested for the higher rate of developing schizophrenia in babies born in spring?

Answer 16

• Brain development is negatively affected by the mother catching an infection during the 2nd trimester (for babies born in spring this would coincide with the winter flu increase)
• The relative lack of sunlight leading to vitamin D deficiency

Question 17

What is permissive experience?

Answer 17

An environment that supports and enables behaviour to be expressed

Question 18

What is instructive experience?

Answer 18

A signal from inducing cell is required for gene expression to occur

Question 19

What is the difference between permissive and instructive experiences?

Answer 19

Permissive looks at expressing behaviour, instructive looks at gene expression

Question 20

What is the difference between critical and sensitive periods?

Answer 20

Critical depends upon the experience in this period whereas sensitive shows that the effect of the experience is the greatest during this period

Question 21

What evidence suggests that exposure to the optical properties of our environment shapes how our sensory systems develop?

Answer 21

Deprive an animal of optical signals coming into one eye, we find that the synaptic connections between axons arriving from the lateral geniculate and the visual cortex become poor. Shows that the development of the cortical visual centre depends on visual stimulation from the environment

Question 22

What evidence suggests that exposure to the acoustic properties of our environment shapes how our sensory systems develop?

Answer 22

Experiment on owls. Animals are raised wearing prism glasses that rotate the visual world by a certain amount. The animal would see something in one place but hear it in another. This reorganises the auditory cortex so that they hear and see on the same place

Question 23

What evidence suggests that our understanding of the work develops on the back of our ability to act in the world?

Answer 23

The visual cliff avoidance.
Prelocomotor infants do not avoid the cliff as they don’t understand the consequences. By 8 months infants show avoidance