# The brain is divided into distinct regions, each responsible for different functions. Explain why scientists find it difficult to study the brain and map the functions of its different regions.

> WJEC A-Level Biology (Wales) — 4.6 The nervous system · Explain · 5 marks

## Mark scheme (5 marks)

1. There are billions of neurones in the brain, making it complex to study
2. The brain must still be working / the patient must be alive in order to study the function of neurones
3. There are ethical issues with studying the brains of patients with brain damage, as they may not be able to give informed consent
4. Studies can only be carried out after damage has occurred, so the damaged brain cannot be compared to the patient's healthy brain
5. Brain damage rarely causes a single problem, so it is difficult to match a specific problem to specific damaged neurones / a specific region

## Related

- [Revision notes for WJEC A-Level Biology (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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