A study conducted in University of California Los Angeles (UCLA) found that the Pavlovian response —a conditioned reaction to a stimulus— originates in a small cluster of brain cells. Interestingly, these are the neurons that malfunction in conditions such as Tourette’s syndrome, Huntington’s disease and Parkinson’s disease. For this reason, the group of UCLA researchers hope their finding may help develop new methods to diagnose and treat these conditions.
For the study, published in Neuron, they conditioned mouse models to react to unfamiliar scents (lemon or banana) which were followed by a drop of condensed milk. After repeating the exercise several times, the mice started to anticipate the sweet reward when perceiving the smell (Pavlovian response), showing it by liking the air fervently.
Then, the researchers tested again the Pavlovian response after silencing different groups of cells in a part of the brain associated with reward, movement and decision-making, called the striatum.
“When we switched off the support cells, the mice licked the air in anticipation of the milk only half as often as normal,” said senior author Sotiris Masmanidis, an assistant professor of neurobiology at the David Geffen School of Medicine at UCLA. “We suspect that the support cells enhance the brain circuits that encode Pavlovian response.”
The influence of the support cells in the conditioning seemed stronger when the mice were first learning to pair the unfamiliar scents with a reward. However, in those mice already conditioned, the change was less dramatic.
According to the authors, the findings suggest that the alteration of support cells, affecting the learning process where a stimulus is paired to a response, can be linked with some neurological disorders, and restoring the neuron’s function may eventually help people with these diseases.
Source: UCLA Newsroom
