To investigate the role of serotonin in patience, the researchers used a task in which mice have to wait for a reward that arrives at random times.
During some of the trials, they stimulated serotonin neurons using a technique called optogenetics."We made serotonin neurons sensitive to light so when we illuminated them, they were activated and released serotonin in the brain," said Madalena Fonseca, member from the team of lead researcher Zachary Mainen at the Champalimaud Centre for the Unknown (CCU) in Lisbon, Portugal.
The scientists observed that when they activated serotonin neurons, mice became more patient."The more serotonin neurons were activated, the longer the mice would wait," added Masayoshi Murakami, another member of the CCU team.
This study has implications for understanding the involvement of serotonin in depression and other diseases. Because antidepressants are thought to increase serotonin, people assume that more serotonin neuron firing would feel good."Our results show that the story is not so simple. That serotonin affects patience gives us an important clue that we hope will help us crack the serotonin mystery," Mainen concluded in a paper appeared in the journal Current Biology.