From Science Daily:
When rats rest, their brains simulate journeys to a desired future such as a tasty treat. Researchers monitored brain activity in rats, first as the animals viewed food in a location they could not reach, then as they rested in a separate chamber, and finally as they were allowed to walk to the food. The activity of specialized brain cells involved in navigation suggested that during the rest the rats simulated walking to and from food that they had been unable to reach. The study, published in the open access journal eLife, could help to explain why some people with damage to a part of the brain called the hippocampus are unable to imagine the future.
“During exploration, mammals rapidly form a map of the environment in their hippocampus,” says senior author Dr Hugo Spiers (UCL Experimental Psychology). “During sleep or rest, the hippocampus replays journeys through this map which may help strengthen the memory. It has been speculated that such replay might form the content of dreams. Whether or not rats experience this brain activity as dreams is still unclear, as we would need to ask them to be sure! Our new results show that during rest the hippocampus also constructs fragments of a future yet to happen. Because the rat and human hippocampus are similar, this may explain why patients with damage to their hippocampus struggle to imagine future events.”