All parts of the brain › Functions › Laughter

What part of the brain controls laughter?

There is no single laugh centre. [1][2][3]

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

Lit: whole parts; region borders not drawn.

Slice

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; .

A coordinating network in the brainstem, around the periaqueductal grey of the midbrain and the reticular core below it, drives the face, the breathing and the voice of a laugh. It is set off from above: the anterior cingulate cortex, the hypothalamus and the amygdala carry the emotional, reactive laugh, while the supplementary motor area on the superior frontal gyrus links that system to the motor cortex used for a deliberate, social laugh. [1][2][3]

The supplementary motor area and the anterior cingulate cortex are regions on these gyri, not separate shapes. 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.

Laughter: 7 parts lit

Superior frontal gyrus, cingulate gyrus, hypothalamus, amygdala, midbrain, pons and medulla oblongata. Tap one to see where it is and what it does.

The parts and their roles

Its inner, rear face holds the supplementary motor area; electrical stimulation of the pre-supplementary motor area and the superior frontal gyrus has made people laugh, a role thought to concern the motor side of laughing, and in tractography the pre-SMA links the emotional and the conversational laughter networks. [4][3][5] Where is the superior frontal gyrus?
Stimulating the pregenual part of its anterior cingulate cortex made half of the people stimulated laugh with a genuine feeling of mirth, and social laughter raises the release of the brain’s own opioids there. [4][3] Where is the cingulate gyrus?
Purely emotional laughter is run mainly from structures below the cortex, especially the hypothalamus; it is more active during reactive laughter, such as being tickled, than during laughing on purpose. [1][2] Where is the hypothalamus?
One of the two limbic-system structures Wikipedia names as involved in laughter (the other is the hippocampus); it lies in the basal temporal lobe, an area that sends input to the brainstem’s laughter centre. [1][2] Where is the amygdala?
Holds the periaqueductal grey, the core of the brainstem coordinating centre for laughter that, with the upper reticular formation, controls the facial expression, breathing and voicing of a laugh. [2][1] Where is the midbrain?
Part of the reticular core of the brainstem, where the pathways for laughter are thought to meet; the conversational laughter network sends its fibres from the motor cortex down through the internal capsule to the brainstem’s motor nuclei. [1][3] Where is the pons?
The lowest part of the brainstem, through which the reticular core runs to the breathing muscles: a laugh is made of very rapid contractions of the intercostal muscles and the diaphragm, large breaths out followed by separate bursts. [2][1][6] Where is the medulla oblongata?

Named areas on the lit gyri

Supplementary motor area, on the : On the midline surface of the hemisphere just in front of the primary motor cortex; its front part is now called the pre-SMA, the part from which stimulation has evoked laughter. [5][4]
Anterior cingulate cortex, on the : The front part of the cingulate gyrus; its pregenual part, in front of the bend of the corpus callosum, is where stimulation evoked laughter together with mirth, and it is also active when watching other people laugh. [4]
The periaqueductal grey, on the : Grey matter around the cerebral aqueduct in the midbrain, named in Wild et al.’s 2003 model as part of the brainstem coordinating centre for laughter. [2]

How they work together

Laughter runs on two partly separate networks, traced in white-matter tractography from sites where stimulation evoked laughter: one, through the pregenual anterior cingulate, the ventral temporal pole and the ventral striatum (nucleus accumbens), reaches the brainstem and is thought to give emotional laughter; the other, from the frontal operculum and primary motor cortex, gives conversational laughter. The two meet in the pre-SMA. [3]
The cortex can hold a laugh back: holding back laughter while being tickled raised activity in motor and premotor cortex, which are thought to inhibit the brainstem laughter centres. [2][1]
Laughter is common and early: in a 1999 study of 80 people, they laughed on average 18 times a day (range 0 to 89), and in conversation there are about 5 laughs per 10 minutes. Babies laugh before they speak, from about 15 weeks to four months of age. [1][2]
It is older than speech: rats, apes and dolphins make sounds like laughter, and chimpanzees laugh differently when tickled and when playing. Laughter uses the same vocal tract as speech, but speech keeps the breath pressure steady with fine control of the rib muscles, while a laugh contracts them very rapidly. [1][2]
Honest limit: these are networks seen in imaging and stimulation studies, not single centres. A 1984 JAMA paper quoted by Wikipedia says there is no known “laugh center” in the brain; the periaqueductal grey and the pre-SMA are not separate shapes in this atlas, so the whole midbrain and superior frontal gyrus are lit. [1][2][7]

Laughter is the outward sign of an emotion: the hypothalamus, cingulate gyrus and amygdala lit here are the limbic parts the emotions page lights for feelings in general. [1] What part of the brain controls emotions?

A laugh is also a facial expression: the brainstem coordinating centre for laughter drives the face as well as the breath, and the frontal operculum, which links emotion to deliberate expression, takes part in smiles and laughs. [2][4] What part of the brain controls facial expressions?

Sources

Facts describe anatomy and normal function only. A part lit here takes part in laughter; 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.