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.

1. The brain contains billions of neurons, creating an extremely complex network that is difficult to analyse in detail.
2. Functional studies require the brain to be active, so the subject must be alive and the brain must be working during the experiment.
3. Ethical constraints prevent invasive experiments on healthy brains, and patients with brain damage may lack capacity to give informed consent.
4. Most studies are post‑damage; the damaged brain cannot be directly compared with the same individual’s healthy brain, limiting causal inference.
5. Damage rarely produces a single, isolated deficit, making it hard to link a specific problem to a particular region or set of neurons.