6.3 The Brain After Trauma & Ways of Studying the Brain: AQA Psychology A level Revision

Plasticity

The brain adapts both its structure and function in response to the environment. These changes could be due to learning a new cognitive process, or a sudden trauma which causes damage to the brain.

Functional recovery

Functional reorganisation – When an area of the brain is damaged, intact regions take over lost functions, so tasks are performed by healthy areas instead.

Synaptic pruning – Connections that are used often are strengthened, while rarely used synapses are eliminated, making neural networks more efficient and communication faster.

Maguire et al.

Maguire et al. (2000) conducted structural MRI scans of 16 male London taxi drivers and 16 matched non-taxi drivers of similar age and education. The posterior hippocampi were significantly larger in taxi drivers, and hippocampal volume increased with years spent driving. This indicates that the adult brain can undergo functional reorganisation, as prolonged spatial-navigation experience is linked to structural changes, supporting the concept of brain plasticity. However, because the study is correlational, it cannot prove taxi driving caused the hippocampal growth—people with naturally larger hippocampi may have been more likely to become taxi drivers.

Danielli et al.

Supports Maguire's findings. Case study of EB, who was 14, and at two years old, EB had to have a hemispherectomy on the left side of his brain to remove a tumour. His language centres were removed, including the Brocca and Wernicke areas. Immediately after surgery, EB had lost all language function, however, after two years EB had recovered his language ability, even without his left hemisphere.

This supports brain plasticity, showing that the brain can adapt and recover after trauma, especially early on in life. Researchers completed fMRI scans and found that the right hemisphere acted as if it was the left hemisphere (like a blueprint) for language.

fMRI- outline and evaluation

fMRI – Measures changes in blood oxygenation (BOLD signal) to produce 3D images of active areas during a task.

• Strength: High spatial resolution (~1 mm) → allows precise localisation of brain function and identification of specialised areas, supporting localisation theory. Non-invasive (no radiation) → safe and repeatable.
  

• – Weakness: Low temporal resolution (~5 s delay) → cannot track fast neural changes. Measures blood flow, so only an indirect measure of neural activity. Also very expensive compared to other neuroimaging techniques

ERP (Event-related Potential)- outline + evaluation

ERP – Uses statistical averaging of EEG data to isolate brain’s specific electrical response to a stimulus.

• Strength: High temporal resolution like EEG but also identifies specific cognitive processes (e.g. P300 linked to attention), giving more detailed insight into brain function.
  

• Weakness: Requires many trials and rigorous controls to filter background noise; small changes in methodology can produce different ERP results → limits reliability.

Post Mortem Dissection- outline + evaluation

Post-mortem – After death, brain is dissected to examine structural/biochemical abnormalities, often in people with rare disorders (e.g. Broca’s “Tan”).

• Strength: Provides direct examination of brain tissue, allowing researchers to establish structural/biochemical abnormalities that can’t be investigated in living patients, forming the basis for understanding brain–behaviour links.
  – Weakness: Causation cannot be confirmed—damage may be the result of illness or death, not the cause of the behaviour; also relies on retrospective data from medical records which may be incomplete.

EEG - outline + evaluation

EEG – Electrodes on scalp record patterns of electrical activity from large populations of neurons.

• Strength: Extremely high temporal resolution (milliseconds) → excellent for investigating real-time brain states (e.g. epilepsy, sleep stages). Non-invasive and inexpensive compared to fMRI → practical for clinical and research use.

• Weakness: Low spatial resolution → signals from many neurons overlap, making it difficult to pinpoint the exact source of activity.