We can get addicted to a wide variety of things, from drugs to the internet, and at times it becomes difficult to imagine life without them. Scientists have found out how our biology and genetic makeup can make us more susceptible to any sort of addiction. It has to do with the connectivity of different parts of the brain and levels of dopamine, the ‘feel-good’ neurotransmitter.
Neuroscientist Shelly Flagel, of the University of Michigan, observed different behaviors of rats after a lever was shown to them which was followed by a reward from the chute. Some, the goal trackers, kept on coming back to the chute after seeing the lever as they were classical conditioned while others, the sign tracker, kept returning to the lever.
Moving further, the scientist using chemogenetics altered the brain circuit connecting paraventricular nucleus of the thalamus (PVT), which drives behavior, and the prelimbic cortex, which is our reward system. This allowed the scientists to turn on or prevent signals from prelimbic cortex using drugs. Activating the circuit led to a decrease in the behavior of sign trackers and deactivating it led to a decrease in the behavior exhibited by goal trackers. The scientists came to the conclusion that motivational signals activated by the stimulus and the increase of dopamine might be causing the compulsive behavior.
These findings might help scientists understand why some individuals are more susceptible to impulse-control disorder. Still, there is a long way to go before we actually find the real cause of addictions and find a valid treatment as this mechanism in humans is much more complex.