(NaturalNews) If you're uncomfortable with the idea that someone can push a button and completely alter your preferences and choices in life, then it's time to become concerned.
Researchers from Massachusetts General Hospital and the University of Leuven in Belgium have discovered that, by stimulating the area of the brain believed to play a significant role in motivation, reward and learning, they could alter preference, successfully predicting and controlling the behavior of primates.
The study will be published June 16 in the online journal Current Biology.
This is the first time that a study has been able to confirm that stimulating the ventral tegmental area (VTA) of the midbrain can change preference and behavior. In previous studies, researchers had been able to correlate increased activity in the VTA with positive events in an animal's experience, but they had been unable to prove that the activity in the VTA caused behavioral shifts.
While studies in rodents had shown that manipulating the VTA affected behavior, this is the first study to bridge the gap between rodent and primate.
In order to test how VTA activation affected primate behavior, researchers placed microelectrodes within the VTA of macaque monkeys using high-resolution magnetic resonance imaging (MRI). The monkeys were then shown a pair of images and allowed to freely choose to look at one image or the other.
Their choice was measured by observing their eye movement. Using a juice reward, the animals were trained to look first at a white square in the center and then at either of the two images.
After a preference for each animal was established, the VTA received mild stimulation whenever the animal happened to look at their non-preferred image. In a relatively short amount of time, the animal's preference changed, and they began to look more frequently at what had initially been their less favored image. When the VTA stimulation was applied again, researchers were able to shift the animal's preference back to their original choice once more.
During a second set of experiments, the animals watched a 20-minute video that presented the two images randomly every five seconds. When the non-preferred image was shown, the VTA was again mildly stimulated. When the preference test was then repeated, the animal's choice was shifted to the image that was reinforced by the VTA stimulation.
Functional MRIs that were taken when the animals received either VTA stimulation or the juice reward showed that both events activated areas of the brain associated with reward-signaling via dopamine production. In fact, the amount of VTA stimulation required was significantly less than the amount required to change or reinforce behavior in previous studies.