AQA GCSE The brain (Biology)

The Brain

The brain and the spinal cord form our central nervous system (CNS).

The brain controls complex behaviour (thinking, memory, emotions, movement).

The brain acts as a control centre.

The brain is made of billions of interconnected neurones and has different regions that carry out different functions.

Brain structure	Function
Cerebral cortex	Conscious thought Memory Language Intelligence Voluntary actions (things you choose to do)
Cerebellum	Coordination of movement Balance Posture
Medulla	Controls automatic / involuntary functions such as heart rate and breathing rate
Hypothalamus	Regulates body temperature
Pituitary gland	Secretes hormones such as ADH

Difficulties investigating brain function

Scientists in the past have had difficulty investigating brain function.

This is because:

1.The brain is very complex, there are billions of neurones, all interconnected. Many areas of the brain work together, not in isolation.

Different regions have overlapping functions, making it difficult to identify the role of individual areas.

2. Brain areas have multiple functions. One area may control several behaviours.

Damage to one area may affect several functions, so results are hard to interpret.

3. Ethical limitations occur.

Experiments are limited by ethical issues, so scientists cannot directly test brain function.

4. Individual variation

People respond differently to brain damage, making results less reliable.

Difficulties treating brain damage and disease

There are problems with treating brain damage or disease.

1.Brain tissues does not easily regenerate.

Neurones in the brain do not readily regenerate, so any damage is often irreversible.

2.Hard to target treatment

Treatments may damage other parts of the brain because functions are closely linked.

3.Drugs affect the whole brain

Drugs cannot easily be targeted to one area, so they may affect other brain functions.

4. Symptoms vary

Symptoms vary between individuals, so treatments are not always effective.

Mapping brain function.

There are several ways that neuroscientists can map brain function.

1.Studying patients with brain damage.

If damage to one area of the brain causes loss of a particular function, that area can be linked to that function.

2. Electrical stimulation of the brain

Stimulating a region of the brain and observing a response shows that this area of the brain is involved in that function.

3.MRI scanning

A standard MRI scan will produce images of the brain
Some types of MRI such as fMRI can show which areas of the brain are active during certain activities such as reading a book.
Used to compare healthy vs damaged brains

Limitiations of these methods.

1.Complexity of the brain

Because brain regions are interconnected, it is difficult to assign a single function to one area.

2.Delicacy of the brain

The brain is delicate, so investigations and treatments risk damaging healthy tissue.

Evaluating the benefits and risks of procedures carried out on the brain and nervous system.

The example below is not one that you should specifically learn, but think of it as how you could apply information.

Example	Benefit	Risk
Removing a brain tumour	Can be life-saving Can reduce symptoms (e.g. seizures, pressure) Can improve quality of life	Damage to healthy brain tissue Infection Bleeding Possible loss of: movement speech memory