Drug and behavioral addictions like gambling are characterized by an intense and focused pursuit of a single reward above other healthier endeavors. Pursuit of the addictive reward is often compulsively sought despite adverse consequences.
In a newly published study, Mike Robinson, assistant professor of psychology, neuroscience and behavior, and integrative sciences explored how our decisions can become narrowly focused onto one particular choice. He and his research team used laser light (optogenetics) to activate the central portion of the brain’s amygdala (CeA), an area normally known for its role in generating responses to drug-related and fearful stimuli.
The study, titled “Optogenetic Activation of the Central Amygdala Generates Addiction-like Preference for Reward,” appears in the May 2018 issue of the European Journal of Neuroscience. Robinson Lab members Rebecca Tom ’16, MA ’17, Aarit Ahuja ’16, Hannah Maniates ’16, and current graduate student Charlotte Freeland coauthored the article and participated in the study.
Members of the Robinson Lab trained rats to choose between two otherwise identical sugar rewards, only one of which was paired with stimulation of the central portion of the amygdala. The researchers found that stimulating the central amygdala created a powerful preference for that one reward, which in some individuals, showed compulsive-like traits.
As Robinson explained, “some rats developed what appeared to be a compulsive preference that defied what was in their best interest.” These individuals displayed addiction-like irrational behaviors, such as ignoring larger alternative rewards or persistently pursuing the reward even when it was paired with painful shocks. “We found that this preference persisted even when a much larger reward was offered as an alternative, or when this preferred reward was paired with adverse consequences such as progressively larger electric foot shock, time delays, or effort requirements.”
The researchers noted that about 20 percent of their rats displayed irrational addictive-like behavior, whereas most others began to seek the alternate reward when the shock reached high levels. This supports findings in humans that show that only a proportion of those who try addictive substances develop develop a problematic relationship with them.
“These results suggest a role for the central portion of the amygdala in focusing motivation and desire to excessive levels, generating addiction‐like behavior that persists in the face of more rewarding alternatives and adverse consequences,” Robinson said.
In addition, Robinson presented a short talk during the Real Art Ways’ Science on Screen event on June 5. Prior to the screening of Chocolat, he spoke to the audience about “The Effects of Sugar on the Brain.”