Investigators from Brookhaven National Laboratory have published research that shows the brain’s inluence in the mechanisms to overeat in obese patients. Interestingly, the research published in the October 17 issue of the Proceedings of the National Academy of Sciences, implicates the same neural circuits that cause addicted individuals to crave drugs:
Wang and colleagues [Gene-Jack Wang from the Center for Translational Neuroimaging at Brookhaven –ed.] studied the brain metabolism of seven obese individuals who had gastric stimulators implanted for one to two years. The stimulator, an investigational device much like a pacemaker, provides low levels of electrical stimulation to the vagus nerve, causing the stomach to expand and produce peptides that send messages of “fullness” to the brain. The device has been shown to reduce the desire to eat. This study provides the first direct evidence of which brain regions are involved in this response and gives new clues to how satiety signals sent by the stomach affect eating behavior.
Participants in the study received two separate positron emission tomography (PET) brain scans two weeks apart: one with the gastric stimulator on, the other with the stimulator off. Participants were not told whether their stimulator was on or off. Prior to the scans, subjects were injected with a radioactively labeled form of glucose, which the scanner could track to monitor brain metabolism…
The changes were particularly pronounced in the hippocampus, where metabolism was 18 percent higher during gastric stimulation. The hippocampus is linked with emotional behaviors, learning and memory, and processing of sensory and motor impulses. The hippocampus also plays a role in the retention of memories related to prior drug experiences in addicted individuals, implying that memories of satiety in the obese might also be stimulated by hippocampal activation.
The stimulators also sent messages of satiety to brain circuits in the orbitofrontal cortex and striatum, which have been linked to craving and desire for drugs in drug-addicted patients.
