A recent study found that rats think about their desires in their sleep, like humans do. In the case of a rat's dream, the object of desire is cheese.

Scientists at the University College London (UCL) conducted research to study the inner workings of rats' minds. Brain activity during rest in rodents, according to the researchers, involves thoughts of food and how to travel to obtain it. 

In the experiment, the scientists collected rats and strapped them a handful to electrodes. The rats looked at food placed in another chamber that they could not access. The scientists monitored brain activity in the rodents as this happened.

The rats were then left to rest in another chamber, and brain activity was again monitored.

Next, while the rats were still strapped to the electrodes, the experimenters let them walk to the food. Brain activity was again monitored.

Comparing the three activities, the scientists found that in the areas of the rats' brains that were stimulated, there exists a similarity in the last two activities. Dreaming and walking for rodents project a motivation to try to get to food. This is further explained in a journal of the findings published in eLife.

According to the lead researcher and the paper's senior author, Hugo Spiers, mammals form maps of their environment in their hippocampus. The brain allows them to form these maps as they look around and explore their surroundings. While the animals are sleeping or resting, the brain replays previous journeys the animals took through the map, also enhancing their memory.

"It has been speculated that such replay might form the content of dreams," says Spiers.

Spiers adds that their findings also suggest that during rest or sleep, the hippocampus constructs fragments of the future. The active place cells that make up a map in a rat's mind allow the brain to simulate or prepare future paths to get to food. Motivation therefore plays a big role in explaining how and why rats can dream about food.

Co-lead author Casswell Barry says that they do not know exactly what these neural simulations are for.

"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," he adds.

The findings in the study conclude, "These results suggest that a hippocampal representation of a visible, yet unexplored environment can be formed if the environment is of motivational relevance to the animal." 

Photo: Alice Rosen | Flickr