thought this was interesting when it comes to thinking about how tac works. there clearly has to be a sufficiently potent shared focal point for laughter to emerge, but the idea of tac tweaking the firing threshold for laughter circuits made sense to me.
Damn Interesting » Humoring the Gelotologists
Scans of healthy, laughing brains have shown activity in the primitive limbic system– a network of structures which deal with survival and emotions. The frontal lobes are also involved, as evidenced by the fact that individuals who suffer damage to their right-frontal lobe often lose their ability to appreciate traditional humor, though they still find humor in slapstick and socially inappropriate jokes. In 1998 Dr. Itzhak Fried at the University of California at Los Angeles discovered that some laughter circuits route through the left frontal lobe as well. He was conducting some electrical stimulation of a teenage girl’s brain in an effort to find the source of her epileptic seizures. As he probed, the young woman abruptly began to smile and giggle. Flummoxed, the researcher asked what she found so humorous. “You guys are just so funny– standing around,” she explained. Moments later she laughed again, this time attributing the amusement to an inconspicuous photograph hanging on the wall. It soon became clear that any prodding of a particular patch of her left frontal lobe resulted in laughter; and each time she assigned blame to whatever happened to be in her field of vision. In the interest of science, Dr. Fried increased the current slightly, and noted a marked increase in guffaw intensity. Another notch, and his patient gushed unrestrained waves of exuberant laughter.