Did you ever wonder what occurs inside your body when something funny happens? What is this thing we have in our brains that makes us say "ha-ha" when someone slips on a banana?
One way to find out is to watch the brain laugh. That's what Dartmouth neuroscientist William Kelley did. He and his team had a number of volunteers watch an episode of Seinfeld while being monitored by an MRI--that's a machine that allows researchers to see which parts of the brain are active at any given time. They then synchronized the MRI data with the laugh track to see how the brain changes when it's registering something funny. There's no one "funny center" in the brain--but the findings were pretty suggestive.
When subjects were looking at something funny, the two regions in their left hemispheres lit up. From previous studies these regions are known to be associated with resolving ambiguity. Is there something in "getting it" that's related to the process by which we work with unclear information until we suddenly see the pattern in it?
A couple seconds later two other brain regions became active, called the insula and the amygdala. The insula is associated with emotion, so it seems likely that this is the brain feeling good when it gets the joke--the "ha-ha" response.
The amygdala is associated with memory formation. As the researchers point out, while you may not be able to remember every plot detail in a Seinfeld episode, you can probably remember the jokes. Humor stays with us, forming a lasting memory. Get it?