A study on rats has revealed that negative experiences in early life changed their brain circuits in a way that increased their vulnerability to stress during adulthood.
Over three years, a four-member team of scientists from the Mumbai-based Tata Institute of Fundamental Research and University of Toronto found that adult rats separated from their mothers two days after birth for three hours daily over 12 days showed long-lasting changes in their responses to an important neurochemical in the brain, serotonin. It also showed that this could contribute to changes in these animals’ anxiety behaviour and response to stress as adults.
Early life experience is important because it overlaps with the critical period when the brain fine-tunes sensory, emotional, visual, touch and language circuits.
“There is a direct dialogue between nature and nurture that is very important in early life,” said Vidita Vaidya, biologist at the city institute.
Previous studies suggested that the amount of serotonin secreted is the same for those with and without negative early life experiences. But this study, published last month in the Journal of Neuroscience, has shown that responses to serotonin via the serotonin 2A receptor are very different in animals that have negative experiences in early life. Receptors are proteins that allow nerve cells to communicate with one another. Changes in the serotonin level in the brain alters mood.