A warm sunny beach? Or, food at the end of a tunnel – we aren’t the only ones to dream of the places we’d like to go.
As humans, when we dream, we often replay the events of the day and think about the future. Perhaps it’s the fear of a looming exam, that annoying song on the radio that you can’t get out of your head, or the route to work tomorrow that guarantees maximum sleeping time. And we’re not the only ones – a recent study from University College London suggests rats also do this.
Spiers and his researchers at UCL’s Institute of Behavioural Neuroscience conducted research on four rats which focused primarily on the part of the brain called the hippocampus. The hippocampus is a part of the brain associated with memory, learning and emotion and is responsible for recording information regarding our surroundings – known as spatial memory.
Just like humans, rats can use their hippocampus as storage for maps of their surroundings. The hippocampus is made up of “place cells” which are neurones that fire when the rats are in a specific location. The place cells have different place fields which fire in different locations providing an analogous map of the location, inside the brain. Measuring the hippocampal activity of rats whilst they explore their environment has shown that different patterns of place cell firing help the rats store locational information.
In the experiment, Spiers and his team assembled a T-shaped route for the four rats. Food was placed at one end of the arm visible to the rats, but purposefully, the path was blocked. The four rats could see the route clearly to the food but the transparent barrier stopped them in their tracks. Then, the team allowed the rats to drift off whilst recording their sleeping hippocampal activity with about 50 electrodes each.
As predicted, when the rats were placed back into the T-shaped track with the transparent barrier and food removed, they knew which route to take. As their hippocampal activity was recorded, their place cells began to fire in the same combinations as they had when they were asleep – suggesting that they had previously dreamed of the route to the food.
Spiers suggests his research shows how animals ‘replay’ their visions and thoughts of the day in their dreams, “it has speculated that such a replay might form the contents of dreams” he says. The research also supports the knowledge of the hippocampus, in its role to imagine future events. People who have a damaged hippocampus struggle to think about the future.
Since the rat and human hippocampus are very similar, this could provide useful information in the future. Research has already been undertaken to manipulate dreams (think, the film Inception) with the hope it could treat diseases such as Alzheimer’s.