Brain Development Flashcards
What are the key elements in the process of brain development?
- Cell formation
- Cell migration
- Axon migration
- Connection formation
Steps of the neural tube forms in the embryo?
- 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
What two things need to happen for the formation of these structures?
- Cell division
- Cell migration
Two types of neural tube migration
- Radial migration
- Tangential migration
What is radial migration ?
Moves directly outwards from the central regions of the tube
What is tangential migration?
Moves at right angles to radial paths
Two methods of migration?
- somal: an extension develops that leads migration, cell body follows
- glial-mediated: Cell moves along a radial glial network
What do radial glial cells develop into ?
Neurons
What is axonal growth ?
The process in which the cells need to form the connections that are needed for them to work with each other
What is filopodia?
As axons form their tip becomes a growth cone and develops finger-like antennae
How do axons know where to connect?
- 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)
What’s the hypothesis called for knowing that axons are capable of migrating precisely to their destinations?
Chemoaffinity hypothesis
Why do axons need to grow ? How do they know where to go?
- 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
What happens to cells that are not correctly connected?
They are likely to die
What are teratogens?
A factor which causes malformation of an embryo (risk factors)
What theories have been suggested for the higher rate of developing schizophrenia in babies born in spring?
- 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
What is permissive experience?
An environment that supports and enables behaviour to be expressed
What is instructive experience?
A signal from inducing cell is required for gene expression to occur
What is the difference between permissive and instructive experiences?
Permissive looks at expressing behaviour, instructive looks at gene expression
What is the difference between critical and sensitive periods?
Critical depends upon the experience in this period whereas sensitive shows that the effect of the experience is the greatest during this period
What evidence suggests that exposure to the optical properties of our environment shapes how our sensory systems develop?
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
What evidence suggests that exposure to the acoustic properties of our environment shapes how our sensory systems develop?
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
What evidence suggests that our understanding of the work develops on the back of our ability to act in the world?
The visual cliff avoidance.
Prelocomotor infants do not avoid the cliff as they don’t understand the consequences. By 8 months infants show avoidance
