Researchers at the University College London have discovered that besides being big fans of cheese and having keen noses rats can dream. According to the study published in the journal eLife rodents think of cheese even when they are asleep, namely they dream about the adventures they go thorough in order to get their food.
The researchers observed the brain activity of the rats when they were exposed to food which they were not able to reach and afterwards they were placed in a room from which they could reach the food. In the first experiment the animals were allowed to look at the food in a T-shaped track which the rats could not have access to. In the second experiment the rats rested in a separate room before they were allowed to have access to the track and reach the treat: a piece of honey-coated rice.
During the resting periods the specialized brain cell activity responsible for navigation indicated that the rats’ brains simulated walking back and forth from the treat which was out of their reach. It means that the animals imagined how they walked along the track even though they had not performed that activity before.
What helps the rats generate a mental map are the place cells in the hippocampus. These cells are often considered the brain’s GPS. Place cells are a type of neuron which activates when the animal finds itself in a certain environment. In order to form a cognitive map each cell will be the equivalent of a specific location. So when the rat moves to a new location the cells will receive a new place. Place cells are very important in creating a spatial context for memories. They adjust constantly to the experience and the location of the brain.
The investigators used electrodes in order to measure the activity of 37 up to 66 place cells. In the second experiment, when the rats were resting the researchers observed how the place cells fired in a pattern which was like the one produced when the rats performed the real journey to the food.
Co-author of the study Dr. Caswell Barry remarked:
“It seems possible this process is a way of evaluating the available options to determine which is the most likely to end in reward, thinking it through if you like. Something we’d like to do in the future is try to establish a link between this apparent planning and what the animals do next.”
This study could shed light on why some people who have injured their hippocampus are not capable of imagining the future.
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