The limbic system, emotion and reward !
- Concept
- For completeness
A ring of brain structures links feelings, memory and motivation, and drives the body's emotional reactions.
Updated 2026-11-01
Also called: Papez circuit, Reward pathway
See it in 3D: Amygdala · Hippocampus · Cingulate gyrus · Fornix · Hypothalamus · Thalamus · Frontal lobe
What it is
The limbic system is a set of structures on the inner edge of each hemisphere: hippocampus, amygdala, cingulate gyrus, fornix, mammillary bodies and connected thalamic and prefrontal areas. It gives emotional value to experience, links emotion with memory, and acts on the body through the hypothalamus. The mesolimbic dopamine pathway signals reward and drives motivated behaviour.
Key facts
- Dopamine in the reward pathway encodes prediction error: it rises when an outcome is better than expected.
- The amygdala receives fast, crude sensory input from the thalamus and slower, detailed input from the cortex, allowing quick reactions to threat.
- Smell connects directly to amygdala and entorhinal cortex, which is why odours evoke strong emotional memories.
- Herpes simplex encephalitis targets the medial temporal and orbitofrontal regions and can produce Klüver–Bucy features.
Clinical notes
- Addiction: repeated drug-induced dopamine surges remodel reward circuits and weaken prefrontal control.
- Temporal lobe seizures often start in the hippocampus or amygdala: déjà vu, fear, rising epigastric sensation, smells.
- Chronic stress and depression are linked to changes in hippocampal volume and amygdala reactivity.
Test yourself
Think of the answer, then tap the question to see it.
Which circuit connects the hippocampus to the cingulate gyrus, and through which structures?
The Papez circuit: hippocampus → fornix → mammillary bodies → mammillothalamic tract → anterior thalamic nucleus → cingulate gyrus → parahippocampal cortex → hippocampus.
Why does fear raise heart rate and blood pressure?
The amygdala activates the hypothalamus and brainstem autonomic centres, increasing sympathetic outflow and adrenal catecholamines and engaging the stress axis.
How do drugs of abuse act on the reward pathway?
They increase dopamine in the nucleus accumbens, directly or by disinhibiting ventral tegmental neurons, producing a reward signal larger than natural rewards.
What does bilateral amygdala damage produce?
Klüver–Bucy syndrome: loss of fear and placidity, hyperorality, hypersexuality and inability to recognise the meaning of objects seen.
See it in 3D
The structures of Durgical's 3D anatomy where it happens.
Related topics
- Learning and memory
- Functions of the hypothalamus
- The main neurotransmitters
- Taste and smell
- The HPA axis and its circadian rhythm
Related conditions
In Biochemistry
In Pharmacology
Educational physiology content; not a diagnostic or treatment guide and no substitute for a health professional's advice. Values are approximate references. No doses are given.
Sources: 13.2 The Central Nervous System (OpenStax (Rice University), 2022); Neuroanatomy, Limbic System (StatPearls (NCBI Bookshelf), 2024); Neuroanatomy, Amygdala (StatPearls (NCBI Bookshelf), 2024); Neuroanatomy, Cingulate Cortex (StatPearls (NCBI Bookshelf), 2024); Hall JE. Guyton and Hall Textbook of Medical Physiology, 13th ed. (ch. 59). Reference book used to check facts; its text and figures are not reproduced (Elsevier, 2016).
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Representative model, for educational purposes only.