The three main divisions of the brain

1. The brain has three main divisions: the cerebrum, the cerebellum and the brainstem.
2. The cerebrum is the large outer part that handles thinking, language and the storage of long-term memories in its outer layer, the cerebral cortex.
3. The cerebellum sits at the back and co-ordinates balance and movement, and the brainstem below it runs automatic functions such as breathing and heart rate while relaying signals between the brain and the body.
4. Memory depends on several regions, so damage to one region produces a particular kind of memory problem.
5. The three pairings to learn are the hippocampus with anterograde amnesia, the frontal lobe with retrograde amnesia, and the cerebellum with procedural memory.

How the brain forms a memory

1. Neurons carry information through the brain as electrical impulses.
2. Each neuron passes its signal on across a tiny gap called a synapse, using chemicals called neurotransmitters.
3. Repeated firing between the same neurons strengthens their connections, and that lasting physical change is the memory trace.
4. Rehearsing or using the information keeps those connections firing, which strengthens the trace.
5. The hippocampus deals with new information first and then passes it to the cerebral cortex, where long-term memories are held, so a memory takes time to settle.

The hippocampus and anterograde amnesia

1. The hippocampus moves new information from short-term memory into long-term memory, so damage there makes forming new long-term memories extremely difficult.
2. Short-term memory often keeps working, so a person can hold a conversation and have no memory of it minutes later.
3. Memories laid down before the damage are usually kept, because they are already stored in the cortex.

The frontal lobe and retrograde amnesia

1. The frontal lobe sits at the front of the cerebrum and organises the search for memories that were laid down before an injury.
2. Damage there breaks that search, so memories of the past become hard or impossible to reach, which is retrograde amnesia.
3. The most recent memories are usually the worst affected, because older ones have had longer to become firmly stored across the cortex.
4. New learning can still work, so a person with retrograde amnesia may form new memories after the injury.

The cerebellum and procedural memory

1. Memory for skills is handled separately from memory for facts and events.
2. The cerebellum co-ordinates movement and holds these well-practised routines, so they run smoothly without conscious effort.
3. Damage there makes practised actions clumsy and badly timed, such as riding a bike or writing at speed.
4. An undamaged cerebellum is why a person with severe amnesia can still sit down and play a piece of music they learned years earlier.

Neurological damage and memory

1. Neurological damage means physical harm to brain tissue, caused by infection, a blow to the head, a stroke, a lack of oxygen or a long-term illness such as dementia.
2. The damage destroys neurons and the synapses between them, so signals can no longer travel the pathway a memory depends on.
3. The effect depends on which region is harmed, whether new memories, past memories, skills or more than one of these.
4. Damage rarely stops neatly at one structure, so a real case often shows a mixed pattern, as Clive Wearing's did.

Turning this into marks

1. Name the region and the specific loss together, because writing that brain damage affects memory does not secure the knowledge mark.
2. Decide first which kind of memory has gone, whether new memories, memories of the past or a practised skill, and let that choose the region.
3. Fill in the middle of the chain by saying what the region normally does and how damaged neurons break that pathway, because a pairing with no mechanism gains no development mark.
4. The mark most often lost is swapping the two amnesias, so keep the hippocampus with anterograde amnesia and the frontal lobe with retrograde amnesia.