The Brain (AQA GCSE Biology): Revision Note

The brain: Basics

• The brain, alongside the spinal cord, is part of our central nervous system

• The brain is made of billions of interconnected neurones and is responsible for controlling complex behaviours

• Within the brain are different regions that carry out different functions

Structure of the brain

• Scientists have discovered that different regions of the brain seem to be responsible for controlling different functions

• These include the following regions:

  • The cerebral cortex:

    • is the outer layer of the brain, which is divided into two hemispheres

    • is highly folded

    • is responsible for higher-order processes such as intelligence, memory, consciousness and personality

  • The cerebellum:

    • is underneath the cerebral cortex

    • is responsible for balance, muscle coordination and movement

  • The medulla:

    • is the region which controls unconscious activities such as heart rate and breathing

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Investigating the brain

Higher Tier Only

• Studying the brain is very difficult; this is because:

  • the brain is very delicate, so can be damaged easily

  • the brain is highly complex; brain regions affect each other, so it is difficult to study parts of the brain in isolation

• This limited understanding means that treating brain damage and disease is very difficult

  • Any potential treatment carries risks of further damage occurring

  • Accidental damage could lead to speech or motor issues, or changes to personality which are permanent

Mapping regions of the brain

• Neuroscientists can map the regions of the brain to their functions by:

  • studying patients with brain damage

    • Patients with brain damage can be studied to determine the specific effects of damaging particular brain regions

    • The most famous example is Phineas Gage, a rail construction worker who survived an iron rod being driven through his head; this affected his peronality, indicating the brain region involved in determining behaviour

  • electrically stimulating different parts of the brain

    • Tiny electrodes can be pushed into different parts of the brain

    • Small jolts of electricity stimulate these regions and the effects can be observed

    • For example, if a region in the brain responsible for movement is stimulated, the movement caused can be observed

  • using MRI scanning techniques

    • MRI scanners produce detailed images of the brain

    • Traditional MRI scanners require patients to lie completely still

    • Functional MRIs can show which regions of the brain are active during different activities, e.g. listening to music or recalling a memory

Benefits and risks of brain investigations and procedures

Brain investigations

• The benefits of brain investigations include:

  • scanning techniques are non-invasive, allowing the brain to be studied from outside the skull

  • fMRI scanners provide real-time information on brain regions and their function

  • scan images allow comparison of patient brains to those of healthy individuals; this aids in locating damage, tumours or disease

• The risks of brain investigations include:

  • traditional MRI scanners require absolute stillness, which is not possible for everyone

  • the interior of MRI scanners can be claustrophobic and stressful

  • MRI machinery is very expensive to run

  • scanners only provide a diagnosis, and cannot provide treatment

Brain procedures

• The benefits of brain procedures include:

  • physical procedures are the only way of treating some brain conditions, e.g. e.g. removing a tumour

  • electrical stimulation can be used to guide surgeons during a procedure

• The risks of brain procedures include:

  • brain tissue is very difficult to access because of the skull

  • physical procedures risk causing damage to delicate brain tissue

  • physical procedures carry risk of infection or neurological side-effects