Health psychology (option): brain regions associated with stress

The amygdala

Part of the limbic system (Unit 2), the amygdala processes emotional information, especially threat and fear. When it detects a threat, it signals the hypothalamus, triggering the SAM pathway and the HPA axis. A highly reactive amygdala may make someone respond to more situations as stressful. Chronic stress may make the amygdala more reactive.

The hippocampus

The hippocampus (memory, Unit 1, and context) has many cortisol receptors. When it detects cortisol, it helps inhibit the hypothalamus, part of the negative feedback that ends the stress response. Prolonged high cortisol may damage hippocampal cells, weakening that feedback (so stress responses last longer) and affecting memory.

The prefrontal cortex and evaluation

The prefrontal cortex (PFC) handles planning, decision-making and regulating emotion. It can evaluate a situation (is it really a threat?) and dampen amygdala activity, which links to cognitive appraisal (Lazarus). Under high stress, PFC functioning tends to weaken, so people may react more emotionally and plan less well.

Putting it together: amygdala raises the alarm; hippocampus and PFC help regulate and switch off the response.

Evaluation: brain scanning (fMRI, Unit 2) gives objective evidence of which areas are active; animal studies allow controlled research on cortisol and the brain but may not generalise to humans; links are often correlational (does stress change the brain, or do brain differences make people more stress-prone?); explaining stress only by brain regions is reductionist.

Worked example

Explain how the amygdala and hippocampus interact in the stress response.

1. The amygdala detects threat and signals the hypothalamus, starting the HPA axis.
2. Cortisol is released and reaches cortisol receptors in the hippocampus.
3. The hippocampus then inhibits the hypothalamus, switching the response off (negative feedback).

Answer: Amygdala switches it on; hippocampus helps switch it off.

Check yourself

1. Which brain region detects threat and triggers the hypothalamus?
   • Amygdala
   • Hippocampus
   • Prefrontal cortex
   • Cerebellum
   Show answer

   Amygdala. Fear and threat processing.

2. Which region has many cortisol receptors and helps switch off the stress response?
   • Amygdala
   • Occipital lobe
   • Hippocampus
   • Adrenal medulla
   Show answer

   Hippocampus. It inhibits the hypothalamus.

3. The prefrontal cortex is involved in stress because it
   • appraises situations and regulates emotional responses
   • releases cortisol
   • releases ACTH
   • produces adrenaline
   Show answer

   appraises situations and regulates emotional responses. Top-down regulation of the amygdala.

4. What may happen to the hippocampus under prolonged high cortisol?
   • It grows larger and more efficient
   • It starts producing CRH
   • Nothing; cortisol does not reach the brain
   • Its cells may be damaged, weakening negative feedback
   Show answer

   Its cells may be damaged, weakening negative feedback. Chronic cortisol can harm the hippocampus.

5. Why is explaining stress only through brain regions reductionist?
   • It uses brain scans
   • It ignores how people think about stressors and their social situation
   • It names three regions
   • It is based on human participants
   Show answer

   It ignores how people think about stressors and their social situation. Cognitive and social factors are left out.

6. Explain the role of the prefrontal cortex in stress.
   Show answer

   The prefrontal cortex evaluates whether a situation is really threatening and can calm the amygdala's response, but under high stress it works less well, so emotional reactions take over.. What the PFC does to the stress response.

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Sources

• Pearson Edexcel International Advanced Subsidiary/Advanced Level in Psychology specification, Issue 6 (November 2024, first assessment January 2026)
• OpenStax Psychology: 14.1 What is stress? (HPA axis, cortisol, general adaptation syndrome)

Last updated 8 November 2026. Spotted a mistake? Tell us.