In a study published in 2000, Vingerhoets and a team of researchers found that adults, unlike children, rarely cry in public. They wait until they’re in the privacy of their homes—when they are alone or, at most, in the company of one other adult. On the face of it, the “crying-as-communication” hypothesis does not fully hold up, and it certainly doesn’t explain why we cry when we’re alone, or in an airplane surrounded by strangers we have no connection to…
In the same 2000 study, Vingerhoet’s team also discovered that, in adults, crying is most likely to follow a few specific antecedents. When asked to choose from a wide range of reasons for recent spells of crying, participants in the study chose “separation” or “rejection” far more often than other options, which included things like “pain and injury” and “criticism.” Also of note is that, of those who answered “rejection,” the most common subcategory selected was “loneliness.”…
Although biological reasons have been proposed, they often seem a bit silly to me. So I tried to dig into the neurobiology literature – and found just about nothing. It’s actually kind of hard; there’s basically nothing, so far as I can tell. What do we know about the neurobiology behind this intensely social behavior?
There are clues from a paper in 2001 crying is somehow related to laughter. Some people suffer from a neurological disorder known as pathological laughter and crying which is exactly what it sounds like: crying at a moderately sad movie or laughing uncontrollably when frustrated. Here is a video of someone with pathological laughter, and here is another video explaining it (and the connection with MS). This is not so surprising when you think about it. After all, who doesn’t know someone who has cried from happiness or laughed at something sad?
These two things may be linked because they are part of a proposed ‘laughing and crying center’ of the brain, located in the brainstem. In fact, anyone who suddenly begins pathologically laughing should be careful as it is a warning sign of a brainstem stroke. This emotional center probably receives input from the cerebellum; a patient who had a lesion in the cerebellar peduncle, which sends information from the cerebellum to the brainstem, was a pathological laugher and cryer. The authors suggest that the cerebellum usually integrates all sorts of social cues to guide behavior but when it cannot do it’s job properly laughing and crying occur inappropriately.
The cerebellum is an accordion-like structure that often gets accused of being a primitive lizard brain. Whenever a structure looks old, people assume it’s archaic and can’t have evolved to do anything new. But the cerebellum has more than three times as many neurons as the whole neocortex, and is responsible for a lot that it doesn’t get credit for. Other portions of the brain that are involved in emotion and social behaviors, such as the serotonin-producing raphe nuclei and the hypothalamus, send information to the cerebellum and damage to the cerebellum is linked to disinhibited and inappropriate social behavior, as well as a generally lower intellect.
The moral of the story is that crying is a response to all kinds of social cues which psychologists are equipped to study while neuroscientists are unable to. About all we can say is that a structure that coordinates social input is playing an intricate role in controlling tears.
Update: I have a new blog post with a little more information. Apparently, stimulating the orbitofrontal cortex – a region connecting to the ’emotion center’ of the amygdala, while also dealing with (positive and negative) reward – is able to cause crying and feelings of sadness.
Parvizi J, Anderson SW, Martin CO, Damasio H, & Damasio AR (2001). Pathological laughter and crying: a link to the cerebellum. Brain : a journal of neurology, 124 (Pt 9), 1708-19 PMID: 11522574