All parts of the brain › Functions › Autonomic nervous system

What part of the brain controls the autonomic nervous system?

The hypothalamus. [1][2][3]

The hypothalamus, the medulla oblongata, the pons, the midbrain, the insula, the cingulate gyrus and the amygdala lit in red on a 3D model of the brain, seen from the front left and above

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Lit: whole parts; region borders not drawn.

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All 7 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; .

It is the control centre for many of the body’s homeostatic mechanisms, keeping temperature, water balance and other internal conditions steady, and it drives both halves of the autonomic nervous system: the sympathetic (“fight or flight”) and the parasympathetic (“rest and digest”). Its orders run down to centres in the brainstem, chiefly the medulla oblongata, which hold heart rate and breathing steady reflex by reflex, while a cortical network of the insula, anterior cingulate and amygdala adjusts them to what you feel and do. [1][2][3]

The anterior cingulate cortex is a region on a lit gyrus, not a separate shape. The 3D model draws only whole gyri, so the gyrus that holds each area is lit; the area’s exact border is not drawn.

The periaqueductal grey is a region on the midbrain, not a separate shape. The 3D model has no shape for it, so the whole midbrain is lit; the region’s exact border is not drawn.

Autonomic nervous system: 7 parts lit

Hypothalamus, medulla oblongata, pons, midbrain, insula, cingulate gyrus and amygdala. Tap one to see where it is and what it does.

The parts and their roles

The integrator: the control centre for many homeostatic mechanisms, regulating both autonomic and hormone (endocrine) output. Its orders leave along two main tracts, the dorsal longitudinal fasciculus and the medial forebrain bundle, to the brainstem, and its hypothalamospinal tract reaches the sympathetic cells of the spinal cord from the first thoracic to the second or third lumbar segment. [1][4] Where is the hypothalamus?
The main brainstem executor: its cardiovascular centre takes in blood-pressure signals from the vagus and glossopharyngeal nerves at the solitary nucleus, its respiratory centre sets the breathing rhythm, and its dorsal vagal nucleus and nucleus ambiguus hold the parasympathetic cells whose fibres leave in the vagus nerve, those of the nucleus ambiguus reaching the heart. [1][5][2][6] Where is the medulla oblongata?
Holds the pneumotaxic centre, which times the switch from breathing in to breathing out, nuclei for bladder control, the lateral parabrachial nucleus that relays blood-pressure signals from the medulla up to the forebrain, and the locus coeruleus, which mediates many of the body’s sympathetic effects during stress. [7][8][9] Where is the pons?
Its periaqueductal grey plays a critical role in autonomic function and contains descending autonomic tracts; stimulating its dorsal and lateral parts sets off defensive responses with a faster heart rate and higher blood pressure, and in the 43-study meta-analysis it came out on the sympathetic side. [10][3] Where is the midbrain?
Part of the core of the central autonomic network, the set of regions active across every kind of autonomic task in the meta-analysis; it steers output through both the sympathetic and parasympathetic systems, the right anterior insula leaning sympathetic in the scans, and it is linked to sensing your own heartbeat. [3][11] Where is the insula?
The midcingulate cortex is another core node of the central autonomic network, and parts of the anterior cingulate cortex came out on the sympathetic side; in fMRI with a simultaneous ECG, dorsal anterior cingulate activity tracked sympathetic changes in heart rate during effortful tasks, matching arousal to effort. [3][12] Where is the cingulate gyrus?
The left amygdala is the third core node of the meta-analysis’s central autonomic network; its central nucleus has direct connections to the hypothalamus and brainstem and takes part in the blood-pressure and heart-rate changes of a fear response. [3][13] Where is the amygdala?

Named areas on the lit gyri

Anterior cingulate cortex, on the : On the cingulate gyrus; its dorsal part tracked sympathetic heart-rate changes during effort. [12]
The periaqueductal grey, on the : Grey matter around the cerebral aqueduct in the midbrain; it contains descending autonomic tracts and plays a critical role in autonomic function. [10]

How they work together

Two halves, one balance: the sympathetic division leaves the spinal cord in the thoracic and lumbar segments and readies the body for “fight or flight”; the parasympathetic division has a craniosacral outflow, from the brainstem and the sacral cord, and runs “rest and digest”. Together they set heart rate and its force, digestion, breathing rate, pupil size, urination and sexual arousal, mostly without you noticing. [2]
The vagus nerve is the main parasympathetic route: it is the longest nerve of the autonomic system and carries parasympathetic fibres to every organ from the neck down to the transverse colon, except the adrenal glands; most of its fibres, between 80 and 90 per cent, are sensory, reporting on the organs back to the solitary nucleus. [2][6]
Homeostasis is a loop of sensor, control centre and effector: for temperature, thermoreceptors in the hypothalamus itself feed a set point that is regularly reset, and autonomic nerves to blood vessels, sweat glands and organs make the correction. [14]
A network, measured: pooling 43 brain-imaging studies of 615 people, Beissner and colleagues found the left amygdala, the right anterior and left posterior insula and the midcingulate cortex active across all autonomic tasks; sympathetic-linked regions sat mostly in the executive and salience networks, parasympathetic-linked ones in the default mode network, and the hypothalamus came out on the parasympathetic side. [3]
Honest limit: the brainstem centres, the parabrachial nucleus, the locus coeruleus and the periaqueductal grey are small clusters of neurons with no shape of their own on this model, so the whole medulla, pons and midbrain light; the cortical roles come from imaging, which sees where activity rises, not what each region commands, and the meta-analysis drew on far fewer parasympathetic studies (8) than sympathetic ones (19); the spinal cord’s sympathetic chain, the ganglia, the gut’s own enteric nervous system and the organs are outside the model. [3][2][15]

The medulla’s cardiovascular centre, the sympathetic accelerator and vagal brake on the heart and the baroreflex that holds blood pressure steady each beat, has its own page. [1] What part of the brain controls heart rate and blood pressure?

The medulla’s respiratory centre and the pons’s pneumotaxic centre, which set the rhythm of each breath, have their own page. [5][7] What part of the brain controls breathing?

The sympathetic surge of fight or flight, and the slower hormone chain of the HPA axis that runs beside it, are on the stress response page. [16] What part of the brain controls the stress response?

Temperature is the textbook homeostasis loop, run from the hypothalamus. [14] What part of the brain controls body temperature?

Sources

Facts describe anatomy and normal function only. A part lit here takes part in the autonomic nervous system; 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.