When people take cocaine, they feel energized, invigorated and perhaps a little jittery. Scientists at the Université de Bordeaux and Centre National de la Recherche Scientifique in France examined the brain circuits associated with cocaine to determine what produces the hyperactivity and high energy associated with the drug. Senior author François Georges and his research team published their findings in the scientific journal Cell Reports this past November.
To determine how cocaine influenced the brain, the researchers used electrophysiology to measure neuronal firing, biological tract-tracers to determine neural connectivity and electrical pulses to stimulate specific brain regions — among other methods. All of the experiments were conducted in rats.
From these experiments, the researchers were able to determine that a group of neurons in the extended amygdala — a brain region associated with emotional regulation, motivation and learning — acts as a relay between the ventral subiculum and the ventral tegmental area. Researchers have previously identified the ventral subiculum as a brain region engaged in goal-directed behaviors that include cocaine seeking. The ventral tegmental area, meanwhile, produces dopamine, a neurotransmitter involved in reward processing, addiction and high levels of energy. This study revealed that together, these brain regions may make up a neural circuit that contributes to cocaine addiction.
The researchers also investigated what would happen if they increased activity in the extended amygdala via electrical stimulation. By artificially increasing the activity in the extended amygdala, the researchers hoped to mimic the effects of cocaine on the brain. After stimulating the extended amygdala for a long period of time, the researchers found that the brain region actually changed its characteristics. Specifically, they found that the extended amygdala started sending more and more activity to the dopamine-producing neurons in the ventral tegmental area. This increase in dopaminergic activity resulted in the rats becoming desensitized to cocaine’s effects — in other words, the rats needed higher dosages of cocaine to achieve the same effects, not unlike a person developing drug tolerance.
What does this all mean?
To summarize, the researchers found that three brain regions — the extended amygdala, the ventral subiculum and the ventral tegmental area — interact with each other when a rat uses cocaine. This neural circuit results in increased levels of dopamine, a neurotransmitter responsible for increased energy, invigoration and happiness. Unfortunately, if the rat overexerts one of these brain regions through repeated cocaine use — via researcher-guided electrical stimulation — the rat’s ability to reap the positive effects of cocaine decreases.
What makes research like this so important? As scientists continue to better understand the circuitry involved in drug use — and drug abuse — new therapies and new medications can be developed to help individuals overcome drug addiction. After this study, scientists are a little more knowledgeable about how cocaine influences the brain, and that knowledge might make all the difference — especially for young brains that are still developing.
The Sovereign Health Group prides itself on following cutting-edge neuroscience research in both mental health and drug addiction so that we can best help our adult and adolescent patients. Sovereign Health Rancho San Diego offers customized treatment plans that include cognitive behavioral therapy, narrative therapy, psychoeducational groups, family systems therapy, equine therapy and yoga. For more information, contact our 24-hour helpline.
About the author
Courtney Lopresti, M.S., is a senior staff writer for the Sovereign Health Group where she uses her scientific background to write online blogs and articles for a general audience. At the University of Pittsburgh, where she earned her Master’s in neuroscience, she used functional neuroimaging to study how the human cerebellum contributes to language processing. In her spare time, she writes fiction, reads Oliver Sacks and spends time with her two cats and bird. Courtney is currently located in Minneapolis. For more information and other inquiries about this article, contact the author at firstname.lastname@example.org