Lauren Jones, a psychology doctoral student at the University of Washington, presented the findings at a press conference during the Society for Neuroscience's annual meeting on Tuesday.
Jones, who worked under the guidance of Associate Professor Jeansok Kim, revealed that the stressed rats took significantly longer to respond to a change in rewards given to them in a maze, and their performances never matched those of other rats that were not exposed to stress.
The researcher further said that another group of rats was given a small dose of the drug muscimol to temporarily inactivate the amygdala, which is located in the forebrain and processes information about fear, stress, and reward.
Such rats remained unaffected by the stress, and performed as well as the animals that were not stressed, Jones added.
"Stress can be long lasting, depending on what it is. The rats that received the drug were tested on the maze the day after they were exposed to stress and it was as if the experience had never happened to them. Inactivation of the amygdala took the stress away," said Jones.
"Whatever stress these rats experienced was not being processed. They seemed to be immune to the stressful experience," Kim added.
Stress is known to contribute to a number of psychopathologies in humans including anxiety, depression, schizophrenia and drug-use relapse.
Neuroscientists believe that research exploring how stress relates to learning, memory, and decision making will help them understand potential problems stressed people experience in their daily lives.
Kim said: "Decision making, both large and small, is part of our lives. People are prone to make mistakes under stress. Look at what has been going on with the stock market. People are under huge amounts of stress and we have to question some of the decisions that are being made."