Return of the Insula

However unlikely it may seem, perhaps someone at the New York Times is reading my blog. Or not. But it is interesting that they ended up following the same tack I took in my recent post on the insula. That is, they followed up their original article highlighting the insula’s role in the addiction to smoking with another article focusing more squarely on the insula itself as an emerging “area of interest” for studies of the brain. (The article is here, but it is, unfortunately, only available to NYTimes Select members.).

As this article points out, the insula is involved in so many different kinds of activity that it is difficult to understand exactly what it does. Because it is buried deeply in the brain, it couldn’t really be studied before the advent of brain imaging techniques, but now we can see that it “’lights up’ in brain scans when people crave drugs, feel pain, anticipate pain, empathize with others, listen to jokes, see disgust on someone’s face, are shunned in social settings, listen to music, decide not to buy an item, see someone cheat and decide to punish them, and determine degrees of preference while eating chocolate.” That’s a lot of lighting up! But as I mentioned in my other post, the bottom line seems to be that the insula “reads” the body’s physiological state and then generates feelings that may in turn bring about actions, thus keeping the body in some sort of balance. Since all mammals have insulas, this means they also have “emotions,” in the sense of “sensations that provoke motivations”: “If an animal is hot it seeks shade. If hungry, it looks for food. If hurt, it licks the wound.” But these sorts of “emotions” are probably not quite the same as the “subjective feelings” that humans experience. As the article discusses, human insulas have developed some new properties. Humans have an expanded “circuit” that conveys more information to the insula, and the insula itself has grown larger, so that the frontal insula can now recast body sensations as “social emotions” like disgust, delight, love, hate, gratitude, contempt, approval, and so on. Further, the human insulas have a special kind of cell, called VENs (von Economo neurons). We don’t really know what these kinds of cells do yet, but they are found not only in humans but also in “great apes, whales and possibly elephants.” So although it seems fair to say that humans probably have more sophisticated “feelings” than most animals, the presence of VENS in those last three species raises some interesting questions about what their emotional lives might be like.