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

Prophetic Rodents: Neuroscientists Find Hints That Rats Dream of the Future by Kelly BulkeleyNew 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 maze with no blockages, so they could reach the new chambers. It turned out the rats’ hippocampal activity when they first entered the new chamber with food was a close match with their hippocampal activity in sleep—the same place neurons that first fired in sleep later fired in waking life, too. The rats seemed to dream of going into that chamber before they actually did so.

The same effect was not found in relation to the chamber with no food. The preceding rest period did not include any hippocampal activity related to the rats’ later experiences in that place. This finding led the researchers to stress the significance of desire and intrinsic motivation in triggering this “preplay” effect.

The ultimate conclusion of the study was that “goal-biased preplay may support preparation for future experiences in novel environments.” These results give us a better understanding of how preplay, or imagination in a more general sense, can “simulate future experiences in environments yet to be actively explored,” in humans and in other species.

The limits of this research are considerable. Only four rats were used as participants; the periods of “rest” were not clearly sleep stages of any specific kind; and the published results depended on an extremely technical analysis that could allow for many hidden errors. These limits should add a note of caution when assessing the possible implications of the research.

That being said, the findings of this study have a clear affinity with theories of dream function that emphasize the values of the anticipatory simulations frequently occurring in dreaming experience. C.G. Jung spoke of “the prospective function” of dreams, Montague Ullman said dreaming worked to maintain an optimal state of “vigilance,” Frederick Snyder viewed sleep and dreaming as a “sentinel” system to prepare for environmental danger, Rosalind Cartwright argued that dreams serve as “rehearsals” for future actions, and Jeremy Taylor has focused on recurrent nightmares as warnings of psycho-spiritual danger in the dreamer’s waking life. Antti Revonsuo and Katja Valli have been developing the “Threat Simulation Theory” as a way of connecting typical patterns in dream content with brain functioning and the evolutionary challenges of our species. In my 2016 book Big Dreams: The Science of Dreaming and the Origins of Religion, I will talk at length about the capacity for creative forethought and visionary insight in dreaming.

All of which is to say, dream researchers from other areas have been working with similar ideas for years, and these new findings from the University College London team are a welcome addition to the accumulating evidence in favor of dreams having some kind of preparatory function that helps to orient the individual toward successful adaptation in the waking world.

Dream Incubation: An Interview with Arianna Huffington

Dream Incubation: An Interview with Arianna Huffington by Kelly BulkeleyThe Huffington Post recently published an interview I did with Arianna Huffington about dream incubation.  She has a long-standing interest in sleep and dreams, along with spiritual curiosity and an appreciation for scientific research–a perfect audience for what I’ve been working on over the past couple of years.  What I told her about dream incubation comes from chapter 15 of the book Big Dreams: The Science of Dreaming and the Origins of Religion (Oxford U. Press), due out in early 2016.  That’s the next-to-last chapter of the book, which starts with a section on the evolution of sleep, laying a scientific foundation for understanding how dreams have emerged in the human species.  The second section looks at empirical patterns in ordinary dream recall and content, drawing on research from the Sleep and Dream Database (SDDb).  The third section focuses on “big dreams,” i.e. rare but extremely vivid and memorable dreams that make a long-lasting impression on waking awareness.  I discuss scientific research on four prototypes of big dreaming that recur especially frequently, throughout history and in cultures all around the world: aggressive, sexual, gravitational, and mystical.  Finally, in the fourth section, I use this information about big dreams to shed new light on several kinds of religious experience found in many different traditions: demonic seduction, prophetic vision, ritual healing, and contemplative practice.  Dream incubation appears in the chapter on ritual healing, with lots of discussion of the Roman orator Aelius Aristides in the 2nd century CE, who wrote about his dream incubation experiences at a temple of the ancient Greek healing god Asclepius.

Children’s Dreams: A Word Search Analysis (part 1)

Children's Dreams: A Word Search Analysis (part 1) by Kelly BulkeleyI’ve just begun a new project using word search methods to study dream reports from children and adolescents.  I thought that showing in real time the steps of my analytic process might help other people learn how to apply these methods to their own dream studies.

Any research project starts with a question.  In this case my question was about “big dreams” in childhood (the subject of a book-in-progress).  I wanted to know more about recurrent patterns in the dreams that children and adolescents remember most vividly.  Other researchers like David Foulkes have studied normal, average dream patterns in children, but my question focused on the distinctive features of highly memorable dreams in the early stages of life

Earlier this spring I contacted Harris Interactive, an opinion research company, regarding their “YouthQuery” survey, which enables a researcher to ask a single question and receive online answers from @1000 American children ages 8-18, along with a few other demographic data points.  (The cost of this survey, while considerable, was no more than I’ve paid research assistants to help with other projects in the past.)

There are pros and cons to online surveys.  On the downside, it’s impossible to validate a person’s answers, and it favors participants who are educated and affluent enough to use computers.  On the upside, participants can give their answers in a private setting in their own words, which is extra valuable for a word search approach.

I try not to let excessive angst about methodology slow me down.  Every study has its limits.  Once you’ve identified them, you move on and do the work.  I’m more interested in discovering what a method can do rather than dwelling on what it can’t do.

The Harris people and I decided to word the survey question as follows:

“We are interested in hearing about a dream that you had and remember a lot about.  Please try to tell us everything you remember about the dream, including where you were, who else was there, what happened, how you felt, what you were thinking during the dream and how it ended.  Please also tell us about how old you were when you had the dream.”

The other questions asked in the standard YouthQuery survey regarded age, gender, race/ethnicity, current grade in school, school location (urban, suburban, rural), and school type (public, private, parochial).

Harris conducted the survey in early April, and then I uploaded the info (thanks to Kurt Bollacker) into the sleep and dream database (SDDB).  The dream reports and answers to the other questions can be seen at:

Making this information publicly available enables others to check my work and test my claims, always a good thing in empirical research.  More importantly, it allows other researchers to explore facets of the data beyond what I or any single analyst can pursue.

Dream researchers have operated for too long with isolated sources of data that never receive more than one investigator’s systematic attention.  Digital databases can help our field move forward into a more dynamic and collaborative future.

Next: testing my first predictions