Brain structure and function

1. Alongside dopamine, the biological explanation covers how the structure and functions of the brain relate to cognitions and behaviour.
2. Scans show brain dysfunction in two ways: differences in brain volume, meaning how much tissue there is, and differences in brain activity, meaning how hard an area is working.
3. MRI scans measure volume, while fMRI and PET scans measure activity by tracking blood flow and oxygen use.
4. The three areas involved are the frontal lobes, the hippocampus and the temporal lobes.
5. The argument is that a difference or damage in these areas disrupts thinking, memory and perception, and those disruptions are the symptoms.

Brain volume

1. Many people diagnosed with schizophrenia have enlarged ventricles, the fluid-filled spaces inside the brain.
2. Larger ventricles mean less tissue around them, so the finding points to a loss of grey matter.
3. Overall brain volume tends to be slightly smaller, and the reduction is clearest in the temporal lobes and the hippocampus.
4. These are averages across groups, so many individuals diagnosed with schizophrenia have scans that look entirely ordinary.

The frontal lobes, hippocampus and temporal lobes

1. Frontal lobes
   1. They handle logic, reasoning, planning, problem solving and judgement.
   2. Activity here is often low, and people with schizophrenia perform poorly on the Wisconsin Card Sort Test, which requires a person to switch sorting rule when the rule changes without warning.
   3. Low frontal activity fits the disorganised thinking and the negative symptoms such as avolition.
2. Hippocampus
   1. It stores and retrieves memories and helps set an experience in its context.
   2. It is often reduced in volume, which fits the difficulty many people report in using and accessing memories.
   3. Heckers (2001) reported abnormal hippocampal activity while people were experiencing auditory hallucinations.
3. Temporal lobes
   1. They process hearing and language, including telling a person's own inner speech apart from a voice in the room.
   2. They have been found to be overactive, reported by Mandal (2002), which fits hallucinations, delusions and disordered thinking.

Neurological damage

1. Neurological damage means physical harm to brain tissue, from a head injury, an infection, a stroke or a tumour.
2. Damage to the frontal lobes leaves planning, judgement and self-control impaired, which shows up as disorganised behaviour.
3. Damage to the hippocampus leaves memory impaired, so new information is not laid down or retrieved reliably.
4. Damage to the temporal lobes makes speech and sound harder to interpret, and can produce hallucination-like experiences.
5. Because damage to these areas produces symptoms that resemble schizophrenia, the theory treats the same areas as involved in the condition itself.

The three main divisions of the brain

1. Cerebrum
   1. The largest division, split into two hemispheres and four lobes, responsible for thinking, memory, language and perception.
2. Cerebellum
   1. Sits at the back and beneath the cerebrum, and controls balance, co-ordination and fine movement.
3. Brainstem
   1. Joins the brain to the spinal cord and controls automatic functions such as breathing, heart rate and the sleep and waking cycle.
4. The frontal and temporal lobes are parts of the cerebrum, and the hippocampus lies deep inside the temporal lobe.

Criticisms of the biological theory

1. The theory sits on the nature side, explaining schizophrenia through dopamine and physical brain differences.
2. It gives little weight to nurture, such as a stressful upbringing, bereavement, poverty, city living or discrimination.
3. Scan findings are correlational, so a difference measured at the same time as symptoms cannot show which came first.
4. The differences may be a result of living with schizophrenia, or of years of anti-psychotic medication, rather than its cause.
5. Not everyone diagnosed shows these differences, and some people who have never been diagnosed do, so the findings cannot explain every case.
6. Nature and nurture both contribute, so biology on its own is an incomplete explanation.

Turning this into marks

1. When two brain findings are asked for, make them genuinely separate rather than one finding rephrased.
2. Name the area and the symptom it is linked to, such as overactive temporal lobes and auditory hallucinations, because a general reference to brain differences does not secure the knowledge mark.
3. The mark most often lost is writing that a brain difference causes schizophrenia when the evidence shows only that the two occur together.