The insula and addiction

There was a news story recently about smokers who suffered damage to a part of the brain called the insula; some of them totally lost their craving for cigarettes. I hadn’t heard much about the insula before that, but here’s a good article from The New York Times about it (free registration required). The insula is small and is buried deep within the brain, but it’s crucial for interpreting physiological data about states such as hunger, heat, cold, and aching muscles and turning this input into a wide range of social emotions. The insula appears to be involved in an astonishingly wide range of experiences, including addiction, anticipation of the future, and emotional appreciation of music. I like the closing line of the article, which refers to the insula as “a crossroads of time and desire”.

All mammals have insulas, but in humans and to some degree in other great apes, the insula is a much more powerful organ that may turn out to play a major role in what it feels like to be human. Part of the difference in humans has to do with the neural pathways that feed information to the insula. Von Economo neurons (VENS, also called spindle neurons) also play a role. VENs are found only in humans, other great apes, whales (you may remember hearing about the discovery last year that whales have them), and maybe elephants; they occur only in the insula and the anterior cingulate cortex, but it’s not clear what exactly they do in the insula.

Shortly after the smoking story came out, my son Greg sent me a link to a story on CNN about how maybe transcranial magnetic stimulation (TMS) could be used on the insula to quell the urge to smoke in smokers with an intact insula, but I wonder what else they might lose in the process.

The NYT article mentions that people who are better at reading the sensations mediated by the insula score higher on tests of empathy, and I found that interesting. Being somewhat emotionally sensitive myself, I’ve wondered about the neurological correlates of that trait. Maybe the insula holds part of the answer.