Oct 3, 2006 ? NEW YORK (Reuters Health) - Scientists from Brookhaven National Laboratory in Upton, New York have identified brain-stomach connections that motivate the desire to over indulge in food.
Specifically, the research suggests an important role for the hippocampus ? the part of the brain associated with motivation, emotion, and memory formation ? in controlling "emotional eating." The work may one day lead to new ways to prevent or treat obesity.
"This study opens new territory in understanding how the body and brain connect to each other, and how this connection is tied to obesity," said Dr. Gene-Jack Wang in a Brookhaven-issued statement accompanying the study in the Proceedings of the National Academy of Sciences.
"We were able to simulate the process that takes place when the stomach is full and for the first time we could see the pathway from the stomach to the brain that turns 'off' the brain's desire to continue eating," Wang explained.
To look at how the human brain responds to "fullness" cues, the scientists implanted a gastric stimulator in seven obese individuals for one to two years. The investigational device provides low levels of electrical stimulation to the vagus nerve, causing the stomach to expand and send "fullness" messages to the brain. The device has been shown to curb the desire to eat.
The subjects underwent brain scans with the stomach stimulator in the on and off mode. Prior to the scans, the volunteers were injected with a radioactive molecule that would light up on the scan so the researchers could track brain metabolism.
"We found that implantable gastric stimulators induced significant changes in metabolism in brain regions associated with controlling emotions, effectively shutting down these obese subjects' desire to eat," said Wang.
The changes were most pronounced in the hippocampus, where metabolism was 18-percent higher with the stomach stimulator turned on.
The stomach stimulator also sent messages of fullness to brain circuits in the frontal cortex and striatum, brain regions linked to craving and desire for drugs in addicts.
With the gastric stimulator on, the subjects self-reported "emotional eating" scores were 21-percent lower than when the stimulator was off.
"This provides further evidence of the connection between the hippocampus, the emotions, and the desire to eat, and gives us new insight into the mechanisms by which obese people use food to soothe their emotions," Wang said. "This new pathway should be explored in further studies to determine if there are any implications for treating or preventing obesity."
SOURCE: Proceedings of the National Academy of Sciences, October 2, 2006.