By Jonny Lupsha, Wondrium Staff Writer
Some unhealthy foods may also be seriously addictive to certain eaters. Recently, health experts have been considering that food addictions may involve more than cravings. Addiction involves multiple regions of the brain.
Specific portions of the brain are deeply involved in the seeking and processing of rewards. These structures are near the septal region of the brain and include the nucleus accumbens, the prefrontal cortex, and the ventral tegmental area. It’s long been established that many recreational drugs affect these parts of the brain, hence their users’ addiction to them. But what if junk food—which is available everywhere and contributes to obesity and type 2 diabetes—did the same thing?
Health experts are now considering that possibility. Some unhealthy foods may in fact have addictive properties that go beyond simply stimulating the taste buds or satisfying a sweet tooth. In his video series The Addictive Brain, Dr. Thad Polk, an Arthur F. Thurnau Professor in the Department of Psychology at the University of Michigan, offered more insight into the neuroscience of addiction.
Reward-Seeking Regions
The nucleus accumbens is often referred to as the brain’s pleasure center, which has been found in both rats and humans.
“This region has been associated with a ride range of pleasures,” Dr. Polk said. “For example, it has been found to be active when rats taste something sweet, when men see pictures of attractive women, and even when mothers are with their babies. The nucleus accumbens is also a major site of action for all drugs of abuse, and it’s thought to play a central role in the euphoric effects that they produce.”
The prefrontal cortex is a region of the cerebral cortex—a tight covering over the brain like bark over a tree—located at the very front of the brain. The prefrontal cortex manages the urges that come from the brain’s reward circuit and can be thought of as the CEO of the brain: It sets goals and delegates them to be carried out. It also helps control addictive behavior.
“The ventral tegmental area, or VTA, is in what’s called the midbrain, at the top of the brainstem,” Dr. Polk said. “Brain cells in the VTA project to both the nucleus accumbens and the prefrontal cortex and can therefore influence both pleasure and self-control.”
Of Lab Rats and Men
In the 1950s, several studies were conducted on humans and lab rats to see what would happen if they could stimulate the pleasure centers in their own brains voluntarily. One study wired electrodes into psychiatric patients’ brains that led to a pushable button which would stimulate certain brain regions. Patients were given control of the button.
Some pushed the button up to 1,000 times and complained when it was taken away, begging for just a few more pushes. Scientists at McGill University performed a similar experiment with rats.
“They implanted an electrode in the rat’s septal region and used a wire to connect that electrode to a lever that the rat itself could press,” Dr. Polk said. “So whenever the rat’s paw hit that lever, it sent electricity to the electrode and stimulated its own brain. The rats would press the lever thousands of times an hour for days on end. There was no evidence that they ever got satisfied or had had enough.”
Dr. Polk said that in another experiment, an electric grid would be placed between the rat and the lever, yet even being shocked wouldn’t stop the rats from reaching the lever. They would not, however, cross the same grid for food. In fact, even between food and the lever when the grid was removed, the rats often chose the lever, starving themselves to death.
Further studies will confirm or disprove the idea of neurologically addictive food.