It's an astonishingly robust finding:
Smokers with damaged insulas were 136 times more likely to have their addictions erased than smokers with damage in other parts of their brains.
What makes this paper so interesting is that it actually makes sense. The insula has been recognized for more than a decade as a crucial substrate for feeling. It sits at an important neural intersection, and is largely responsible for integrating signals generated by our body - so called "somatic markers" - into mental states. As Antonio Damasio has written (his wife is a co-author on the cigarette paper): "The body contributes more than life support. It contributes a content that is part and parcel of the workings of the normal mind."
What is this mental content? Damasio has shown that these bodily signals are the essence of our conscious emotions. (William James proposed a similar theory in 1882.) Damasio has chronicled the lives of patients whose brains are missing this intricate body-brain connection, normally due to damage in the VMPO. Although they maintain full sensory awareness of their body, these patients are unable to translate their fleshy sensations into emotions. The pounding of their heart never becomes a feeling of fear. A smile doesn't cheer them up. Because their mind is deprived of their flesh, they live in a cocoon of emotional numbness.
But back to smoking: how does the insula make us addicted to cigarettes? According to this paper, it detects the bodily rituals associated with smoking - the escalated pulse, the slow inhalation, the slight nicotine rush - and combines them with the idea of a cigarette. When we crave a cigarette what we are actually craving are these bodily changes: they are the emotional core of addiction:
Based on the experiences related by the insula-damaged patients, he suspects that the insula is needed create the feeling that smoking is a bodily need. Bechara notes that other research has suggested that the bodily effects of smoking--particularly the effects on the airways--are a crucial part of the satisfaction smokers get from puffing away. If so, he speculates, smoking cessation therapies such as denicotinized cigarettes may ultimately prove more effective than nicotine patches because they provide physical sensations that stimulate the insula and satisfy the smoker.
That said, I wouldn't go out and lesion my insula to cure my cigarette addiction. One of Damasio's most surprising discoveries is that the feelings generated by the body are an essential element of decision-making. Although we typically assume that our emotions interfere with reason, Damasio's emotionless patients proved incapable of acting "rationally". After suffering their brain injuries, all began displaying disturbing changes in behavior. Some made terrible investments and ended up bankrupt; others became dishonest and anti-social; most just spent hours deliberating over irrelevant details. According to Damasio, their frustrating lives are vivid proof that rationality requires feeling, and feeling requires the body. Your insula might make you addicted, but it also makes you wise.
- Log in to post comments
Fascinating, especially the observations at the end. I've always thought that there was/would prove to be something wrong with the bright line that we try to draw between 'thinking' and 'feeling.'
Nietzsche said it best: "There is more reason in your body than in your best wisdom." If you believe Damasio - and the somatic marker hypothesis remains controversial - then Nietzsche was right. You might also be interested in looking at some of the experiments using the Iowa Gambling Task.
It wasn't William James who said it first--Siddhārtha Gautama suggested this a long time ago (just a pedantic comment--sorry).
I think there's a really funny joke in the notion that brain damaged people give up smoking more easily than people with their full faculties - but it hasn't come to me yet.
This is fascinating. My mother had an operation on a brain tumor about 12 years ago and had to have part of her insula removed. I asked the surgeon then (totally ignorantly) if he could remove the part of her brain that made her smoke -- she was a pack-and-a-half smoker for over 20 years. He said that that was a good and very interesting question, and suggested that before they sent her home, I should remove/toss any smoking-related items from her apartment (cigarettes, lighters, ashtrays, etc.) that could cause her to "remember" that she smoked. Upon her return, she did indeed "forget" her smoking addiction and has been smoke-free ever since. Good to know that there's real science behind this -- at the time I thought it was almost black magic!
I guess my question is, was it the surgery, the removal of the smoking-related stuff, or a combination of both?
If I may be so bold, em, it's pretty obviously a removal of both. Franky, fMRI research is taking on some uncomfortable habits to my mind. Everything I've seen that's been pushed in the non-academic media for the past few years has involved one of three structures: the amygdala, the insula, or the prefrontal cortex (if one can even call that a structure). Claiming that *cigarette addiction*, even addictive behaviors in general, can be associated with one part of the brain is disturbingly simplistic. Seventy years ago a great advance in medical science comprised twirling a loop of wire through disturbed folks' frontal lobes - I hope we're more careful this time around in knowing that association (between GROSS brain region X and GROSS behavior-pattern 2.1) should by no means suggest one-to-one causation y (burn the durn thing out and you'll be FINE!). Believe me, I'm super-glad that your mom quit smoking - I'm just dubious of research that elucidates 18th-century-style medical discoveries when we're in need of 21st-century solutions.
If it just were the "bodily effects of smoking" different kinds of cigarettes would not matter, which is not the case since avid smokers are aware of the different "flavors" and avoid them if they can. Unless of course different "flavors" produce different effects on the airways which seems unlikely.
I am the author of this study. This is a very interesting and thoughtful discussion of this finding. Regarding em's story about his/her mother: it is amazing and gratifying to hear the personal accounts of people whove undergone this change. Given the number of people I've heard from personally, it's strange that no physician has ever picked on this before. With respect to Christine's post: We have never clained that cigarette smoking can be associated with one part of the brain. In fact, we would expect similar effects to occur after lesions in areas such as the nucleus accumbens. This research has an 18th century feel since it uses the lesion method, which is what makes it kind-of cool in my opinion (though not in any phrenological sort of way). Remember that functional brain imaging only tells half the story. As you mentioned, the prefrontal cortex (specifically the orbitofrontal cortex) is implicated strongly by functional imaging studies in addiction. If you read our study, you will see that damage to the OFC doesn't alter addiction to smoking, whereas damage to the insula does. Please don't think that we are saying that smoking addiction = the insula. We are al good cognitive neuroscientists here and think that this is rather an oversimplification that is often indulged by the media.
If I may be so bold, em, it's pretty obviously a removal of both. Franky, fMRI research is taking on some uncomfortable habits to my mind. Everything I've seen that's been pushed in the non-academic media for the past few years has involved one of three structures: the amygdala, the insula, or the prefrontal cortex (if one can even call that a structure). Claiming that *cigarette addiction*, even addictive behaviors in general, can be associated with one part of the brain is disturbingly simplistic. Seventy years ago a great advance in medical science comprised twirling a loop of wire through disturbed folks' frontal lobes - I hope we're more careful this time around in knowing that association (between GROSS brain region X and GROSS behavior-pattern 2.1) should by no means suggest one-to-one causation y (burn the durn thing out and you'll be FINE!). Believe me, I'm super-glad that your mom quit smoking - I'm just dubious of research that elucidates 18th-century-style medical discoveries when we're in need of 21st-century solutions.