Scientists Tie Part of Brain to Urge to Smoke
New York Times
January 25, 2007
By BENEDICT CAREY
Scientists studying stroke patients are reporting that an injury to a specific part of the brain, near the ear, can instantly and permanently break a smoking habit, effectively erasing the most stubborn of addictions. People with the injury who stopped smoking found that their bodies, as one man put it, “forgot the urge to smoke.”
The new finding, which is to appear in the journal Science on Friday, is likely to alter the course of addiction research, pointing researchers toward new ideas for treatment, experts say. While no one is suggesting brain injury as a solution for addiction, the findings suggest that therapies might focus on the insula, a prune-sized region under the frontal lobes that is thought to register gut feelings and is apparently a critical part of the network that sustains addictive behavior.
Previous research on addicts focused on regions of the cortex involved in thinking and decision-making. But while those regions are involved in maintaining habits, the new study suggests that they are not as central.
The study did not examine dependence on alcohol, cocaine or other substances. Yet smoking is as at least as hard to quit as any habit, and it probably involves the same brain circuits, experts said. Most smokers who manage to quit do so only after repeated attempts, and the craving for cigarettes usually lasts for years, if not a lifetime.
“This is the first time we’ve shown anything like this, that damage to a specific brain area could remove the problem of addiction entirely,” said Dr. Nora Volkow, director of the National Institute on Drug Abuse, which financed the study, along with the National Institute of Neurological Disorders and Stroke. “It’s absolutely mind-boggling.”
***
The insula, for years a wallflower of brain anatomy, has emerged as region of interest based in part on recent work by Dr. Antonio Damasio, a neurologist and director of the Brain and Creativity Institute. The insula has widely distributed connections, both in the thinking cortex above, and down below in subcortical areas, like the brain stem, that maintain heart rate, blood pressure and body temperature, the body’s primal survival systems.
Based on his studies and others’, Dr. Damasio argues that the insula, in effect, maps these signals from the body’s physical plant, and integrates them so the conscious brain can interpret them as a coherent emotion.
The system works from the bottom up. First, the body senses cues in the outside world and responds. The heart rate might elevate at the sight of a stranger’s angry face, for example; other muscles might relax in response to a pleasant whiff of smoke.
All of this happens instantaneously and unconsciously, Dr. Damasio said — until the insula integrates the information and makes it readable to the conscious regions of the brain.
***
“The question is, Can you learn to deactivate the insula?” said Dr. Volkow said. “Now, everybody’s going to be looking at the insula.”
Fascinating stuff. It occurs to me that what's being revealed here is the functional integration of addictive behavior, that is, how a human being organizes itself to be addicted.
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