Introduction to the Brain

Question 1

What is meant by a topographic representation, and where is this found in the brain?

Answer 1

A topographic representation is found in the cortex. Here, there is mapping of different body parts, e.g. if the fingers are touched, this is represented in a different part in the cortex to if the back is touched.

Question 2

How does sight work?

Answer 2

1. Light hits the retina, which is a 2D concave bowl of cells.
2. Neurons in the retina are excited and this excitation is carried to the neurons in the back of the brain.
3. An image is formed at the back of the brain.

Question 3

How does smell work?

Answer 3

• There are many randomly organised neurons with olfactory senses in the nose.
• There are neuronal receptors which are responsible for each different smell, and these come together in the brain to determine what the captured smell is.

Question 4

Is the cortex plastic or static?

Answer 4

It is plastic as it changes with age and experience.

Question 5

What are some properties of glial cells?

Answer 5

• The number of glial cells is around the same as the number of neurons.
• Glial cells send broad, long range and long wavelength signals.
• Signals from glial cells are slow.
• Glial cells are involved in brain activity when sleeping.
• Calcium signalling is important in glial transmission.

Question 6

What are NG2 cells?

Answer 6

NG2 cells are neither neurons or glia, as their morphology is that of glia, but their electro-physiology is that of neurons. They can switch to become neural stem cells.

Question 7

How can olfactory bulbs (smell) be used to treat paralysis?

Answer 7

Olfactory bulbs are the only part of the brain where nerve fibres are constantly regenerating. By injecting cells from an olfactory bulb into the spinal cord, a bridge can be provided for nerve fibres to grow back and repair the spinal cord.

Question 8

What is optogenetics?

Answer 8

Activating neurons using light or heat to see how neural circuits determine behaviour.
- GFP based calcium reporters (G-cam) is often used to see neurons firing.

Question 9

Why do we sleep?

Answer 9

While sleeping, all waste is removed from the brain.

Glial cells open water channels, which releases water to wash out the waste. This is then expelled.

Question 10

Why is the fruit fly used to study the human brain?

Answer 10

Both brains are modular.

Question 11

How do we test for behaviour in the brain?

Answer 11

1. Take a gene network.
2. Map neural circuits.
3. Test what each circuit does, one at a time