Prophetic Rodents: Neuroscientists Find Hints That Rats Dream of the Future

New findings from brain researchers at University College London in the U.K. suggest that sleeping rats have the capacity to imagine a place they have never been in waking. This intriguing study does more than support the idea that many animals do indeed dream, in modes appropriate to the neural capacities and environmental experiences of their species. Beyond that, the study shows that rat dreams may have one of the key features of human dreaming, namely the ability to simulate future scenarios and prepare for anticipated efforts to achieve our goals.

Titled “Hippocampal place cells construct reward related sequences through unexplored space” and published in eLife on June 26, the researchers built on previous work showing the importance of the hippocampus in remembering places and forming mental maps of where we have been. The hippocampus is also important for imagination, forethought, and planning future goals. Crucially for this study, the hippocampus is active in waking and sleeping, and researchers have long known that the same hippocampal “place neurons” triggered into firing by a waking-life experience of a particular place will also fire during sleep. The challenge of this study was to find out if hippocampal neurons associated with a place will fire in sleep before any waking experience of the creature actually being in that place. In other words, will the sleeping brain anticipate a desired action? Will it dream of the future?

The experiment involved training rats (with electrodes implanted in their brains) to run through a maze where they could see, but not reach, another chamber where food was visibly located. The rats could also see but not reach an additional chamber with no food. During rest periods, the researchers recorded the rats’ hippocampal activity. Then the researchers let the rats run through the —> Read More