The Intrinsic Relationship Between Imagination and Memories
And where both reside in the brain
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At first glance, memories and imagination might seem like opposites on a spectrum. Memories are based on reality with real people, events, and places, whereas imagination is precisely the opposite.
Imagination inspires a quality of magic and incandescence that defies our material plane of existence. Meanwhile, our memories revolve around data collecting, labeling, and archiving our experiences.
Each memory has a purpose, a reason for being stored away instead of discarded — while imagination is wild and often irrational. But science is beginning to show that the two have more in common than meets the eye. In fact, not only are memory and imagination intrinsically connected, but they reside in the same area of our brain.
An Interdependent Relationship
If you think about it, imagination and memory are comprised of essentially the same ingredients — they both take bits and pieces of our thoughts, emotions, and experiences and combine them with things we’ve read, learned, seen, and heard about. Sometimes this combination better predicts a future outcome, while other times, it creates something entirely new, like a fictional story or a work of art.
Either way, imagination, and memories are more than similar to each other. As a cognitive neuroscientist at the Rotman Research Institute in Toronto and the University of Toronto, Donna Rose Addis summarizes: “Memory is a form of imagination.”
Other experts, such as Loren Frank, a systems neuroscientist at the Howard Hughes Medical Institute and the University of California, San Francisco, believe imagination may explain why we remember anything at all — because remembering our past helps us make better decisions in the future. Frank states:
“From an evolutionary perspective, we are reasonably sure that the purpose of memories is actually in the future. Memories allow you to take experiences that you have and retrieve them to make predictions about what will happen next.”
And vis versa. Not only do we form memories of things we’ve actually experienced, but we also create memories of our mental simulations of what might happen. Imagining possible outcomes, solutions, and decisions, then storing them away as memories, helps us put them into action by giving us something to draw from.
And experts have recently learned that both processes — remembering what we’ve actually done and what we could do — are encoded by the hippocampus.
Hippocampus Home Sweet Home
Studies involving animals, specifically the neural activity in rats, have resulted in a growing pile of evidence suggesting that the hippocampus plays a vital role in imagination.
The first convincing evidence that imagination has a home within our brain at all came from John O’Keefe’s 1971 discovery of “place cells” within the hippocampus, which later helped him win a Nobel Prize in 2014.
O’Keefe and his colleagues found that when rats run a maze, specific brain cells in the hippocampus predictably change based on the animal’s location in the maze. These cells, named “place cells,” tell animals where they are in the world.
At first glance, the function of place cells doesn’t seem relevant to the imagination. But Frank and his team found that place cells don’t always indicate where an animal’s physical location actually is. Sometimes they represent where the animal could be.
See, Frank and his colleagues figured out that the place cells in the brains of rats fire off patterns that repeat about eight times per second, producing a theta rhythm. Within each cycle, these patterns alternate to represent any of three different possible locations the rat could be that are separated in time. The location it just was (memory), its current position, and a potential (imaginary) place it could be in the near future.
A postdoctoral researcher at the Mortimer B. Zuckerman Mind Brain Behavior Institute at Columbia University and a co-author of the paper, Kenneth Kay, explains:
“The neural activity has this unmistakable structure where, at certain time points, it looks like what the animal is experiencing in the present. At these other time points, it looks like an imaginary experience.”
While this form of imagination coincides with Frank’s earlier argument that imagination exists for this exact purpose — as a survival technique — by using it to help us make better future predictions. There is another form of imagination that doesn’t seem to depend on our survival or where we’re traveling to.
This type of imagination occurs when animals are spacing off or doing something mundane or relaxing like grooming. Experts detect bursts of activity called “sharp wave ripples” in the hippocampus during these instances. These ripples also seem to happen when animals sleep, and they appear to indicate the mental replay of past experiences. However, the relationship between sharp wave ripples and memory functions of the hippocampus is poorly understood.
Still, the replays happen about ten times faster than the actual event. Meaning the brain reviews past and possible events ten times faster than in real life, allowing us to run through scenarios quickly.
Things held true in human studies. One 2007 study found that brain scans of healthy people showed that the hippocampus was engaged the most when the participants imagined the future compared to when they thought of the past.
All of this evidence is further supported in Frank’s most recent research, published in October 2022, where he argues that imagination is a fundamental function of the hippocampus. He states:
“[The hippocampus is] still responsible for creating memories of what is happening right now. And now it seems it is also responsible for rolling out possibilities.”
That said, the hippocampus isn’t the sole producer of imagination, but it is the leader. The hippocampus cues up neurons in other brain regions involved in our senses that are either part of a memory from an actual past event or can “fit together in some imagined thing.”
Perspective Shift
Still, even though we know now where the imagination lives, there is another mystery researchers hope to tackle next — and Frank is already on the case. The mystery of how we’re able to separate real life from imaginary. As Frank says,
“It’s amazing that we’re not all psychotic all the time, that we’re not all delusional, because our brains are clearly making stuff up a lot of the time about things that could be.”
In April 2023, Frank and his team published new data suggesting that the brain uses our sensory input — like the feeling of our foot hitting the ground when we walk — to categorize what is real life versus what’s imagined.
So, in essence, the brain seems to separate fact from fiction based on the information it receives from the outside world and how it reconciles with its internal models.
As elusive and wild as our imagination feels, it has a precise location in our brains and procedures in place to distinguish what’s imagined from reality. It seems likely that imagination likely evolved as a survival technique, but it didn’t stop there. It’s grown into something capable of dreaming up entirely new worlds, sounds, people, and a never-ending stream of ideas.
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Fascinating!! And so well presented, as usual! I imagine you're pleased with how this article came out? ;-) Best, Alex