All parts of the brain › Hunger

What part of the brain controls hunger?

Chiefly the hypothalamus. Its arcuate nucleus senses hormones in the blood (ghrelin from the stomach before meals, leptin from fat tissue, insulin) and has two opposing groups of neurons, one raising appetite and one lowering it. The nucleus of the solitary tract in the medulla gathers signals from the gut through the vagus nerve, such as how stretched the stomach is. Taste reaches the insula, and the orbitofrontal part of the prefrontal cortex tracks how rewarding a food is. [1][2][3][4]

The 3D brain needs JavaScript. The list of parts still says what each one does for hunger.

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All 5 parts are lit together. Drag to turn, pinch or scroll to zoom, tap a part on the brain or a name in the list to focus it; .

Hunger: 5 parts lit

Hypothalamus, medulla oblongata, brainstem, insula and prefrontal cortex. Tap one to see where it is and what it does.

The parts and their roles

Its arcuate nucleus holds NPY/AgRP neurons that increase appetite and POMC/CART neurons that decrease it; both respond to leptin and ghrelin and signal on to the paraventricular nucleus and the lateral hypothalamus, which was long called the feeding centre. [1][5] Where is the hypothalamus?
Its nucleus of the solitary tract receives taste and signals from the stomach and intestines through the vagus and glossopharyngeal nerves, and the nearby area postrema, which lacks a full blood–brain barrier, samples hormones in the blood. [3][6] Where is the medulla oblongata?
Carries the vagus nerve, the main line between the gut and the brain, into the medulla, and relays gut and taste signals upward through the parabrachial nucleus of the pons to the hypothalamus, amygdala and thalamus. [7][8] Where is the brainstem?
The primary taste cortex lies in the anterior insula and the nearby frontal operculum; it receives taste signals by way of the thalamus and identifies what a taste is. [4][9] Where is the insula?
The orbitofrontal cortex, on the underside of the prefrontal cortex, holds a secondary taste area where the response to a food falls as you eat your fill of that food, encoding its reward value. [10][4] Where is the prefrontal cortex?

How they work together

Two hormones pull in opposite directions: ghrelin, made mostly by the stomach, rises before meals and falls after them, while leptin, made by fat tissue, reflects the body’s longer-term energy stores and damps appetite. Both act on the arcuate nucleus. [11][12]
Inside the arcuate nucleus the two groups oppose each other: ghrelin switches on the NPY/AgRP neurons, leptin switches on the POMC/CART neurons and quiets the NPY/AgRP ones, and AgRP directly blocks the melanocortin receptors the POMC side acts on. [1][13]
Fullness during a meal comes mostly from the gut: stomach stretch and hormones such as cholecystokinin act on the vagus nerve, and the medulla’s nucleus of the solitary tract passes the message on to the hypothalamus. [14][15][3]
Sensory-specific satiety: after eating one food to fullness, its taste and smell become less rewarding while other foods stay appealing, a fall tracked by neurons in the orbitofrontal cortex; it is why there is often room for a dessert. [16][10]
Honest limit: the arcuate nucleus is only a few millimetres across and has no separate piece on this model, so the whole hypothalamus lights; the stomach, gut and fat tissue that send many of the signals are outside the brain, and much of the detail about these neuron groups comes from studies in mice and rats. [1][2]

Sources

Facts describe anatomy and normal function only. A part lit here takes part in hunger; it does not do it alone, and it does other jobs too. The 3D model is the adult male BodyParts3D brain (credits and licence); on it the brainstem includes the midbrain, pons and medulla, so lighting the brainstem lights all three.