Employees of the School of Medicine at the University of Pittsburgh conducted a study on rats. It showed that the destruction of memories of external factors associated with the use of narcotic substances changes behaviour.
According to JAMA (Journal of the American Medical Association) of 2014, 40-60% of people undergoing treatment for alcohol or drug addiction relapse, negating all the effort and resources expended.
Since the time of Pavlov, it has been known that the brain connects certain external stimuli with a particular behaviour through its response. For example, the sight of a spider triggers a fear response and causes you to take a step back, and the smell of fresh pastries from the bakery stimulates salivation.
When the rats pressed a lever, they received an infusion of cocaine accompanied by sound and light signals. The result of such learning was the assimilation of the associative connection of the audiovisual stimulus with narcotic intoxication. Then at subsequent signals, the rats showed behaviour aimed at finding the drug and they constantly pressed the lever. The next step was to give sound and light signals without injecting the drug to break the connection between memories and stimuli.
This method of exposure is called exposure therapy. It is successfully used in the treatment of phobias, addictions and post-traumatic disorder in humans.
The method has one limitation however, an unstable efficiency when changing external conditions. So it happened in the framework of the experiment with rats. In a different environment, they continued to look for the drug in response to an audiovisual stimulus.
Then the researchers applied optogenetics—a relatively young method of “erasing memories”, discovered in 2005 by Carl Disseroth. With the help of light pulses, the researchers acted on the light receptors of neurons—cells designed to receive, process, store, transmit and output information. As a result of such exposure, memories associated with the cocaine stimulus were erased. This was confirmed by a significant decrease in the intensity of the rats pressing the lever in response to sound and light signals. It turns out that the destruction of connections between memories and stimuli changed the behaviour of rats. The experiment was repeated in other external conditions, and the result was positive.
Light “selective shutdown” of neurons through the retina of the eye in combination with behavioural psychotherapy opens up new opportunities for the treatment of addictions. So far, experiments have been carried out only on animals, because genetic modifications of the human body are currently unacceptable. However, according to scientific data, optogenetic methods can be used in the future to restore or improve memory, treat Parkinson’s disease, anxiety disorders and epilepsy, as well as alcohol and drug addiction.