The Silent Cartographer

The science behind the mapmaking of our memories

Almost every place you’ve ever been has been recorded by your brain. If you’ve been someplace where something significant happened, then your brain probably remembers a lot of detail about where you were. Noted, analyzed, and stored into your subconscious, the location of that event was tied to that memory from the moment it happened. This isn’t just philosophical speculation on our inner workings, it’s bona fide scientific speculation (and hopefully soon to be fact).

Within the past 5 years or so, such progress has been made on the topic of how the brain interprets and utilizes location. One finding that scientists have made is on a process called episodic memory formation.

It’s hypothesized that through this process, our brains solidify our memories by connecting them to the where of when from which they formed. Multiple different stimuli are involved in this process of memory making, which most likely occurs in a central location of the brain called the retrosplenial cortex. Here, all the sensory information gathered from being in a new environment is decodified and interpreted to create explicit meaning for the brain’s user. The Atlantic provides an excellent example of this phenomenon.

“When you walk into someone’s office, your brain records the location of the pieces of furniture, screens, bookshelves and windows inside…Your brain may not remember the arrangement of that office if nothing important happens inside — in fact, you’ll probably forget it — but if something memorable does happen, you will commit the setup of that room to your memory. That room will be forever linked to what you learned inside it.”

It’s crazy isn’t it? The fact that each of our memories is immutably attached to a location makes questions like “Where were you when the Seahawks won the Super Bowl?” all the more relevant. By asking where, we more easily call upon the what of the memory; the specifics that make that memory unique. But how does the brain drag in all this locational information to the brain in the first place?

I’m the map, I’m the map, I’m the map, I’m the map

There’s another background process in the brain that occurs whenever you step into a room. Using specialized cells (called grid cells) within the hippocampus region, your brain begins to map your surroundings by laying a grid pattern made of triangles (equilateral to be specific), over every surface visible to your eyes. As you walk along, moving form triangle to triangle in your mind, your brain taking note of which triangle you occupy at any given time, other cells begin to fire off.

Pass a wall or a fence, a boundary cell will fire off. Move your head left, right, up, down, straight ahead, behind you? BOOM, head direction cells spark, keeping you oriented about where you are within the imagined grid. Pass by a potted petunia, a cat mural, and go through a doorway? Place cells activate, taking note of these events as “landmarks” that give context to where you are on the map.

The combined work of all these cells creates a mental map of your location that allows you to imagine the space in your mind and wander around it as if you were really there. It’s as if your brain is a cartographer, commissioned to survey your every destination and chart it out for future reference should you ever need to revisit that place without travelling there.

Location, Location, Location

How about our memories’ ties to location?

Jim Corder’s piece, “Argument as Emergence, Rhetoric as Love,” started me thinking about the concept of identity, or as he names it, our “narrative.” What are our narrative’s made of, I wondered? In response, he replies:

“The choosing we do to make our narratives (whether or not we are aware of the nature of our choosing) also makes our narratives into arguments.” [p.18, Corder]

And then he says:

“Our narratives are the evidence we have of ourselves and of our conviction…argument is what we are.” [p.18, Corder]

Layman’s terms version of these quotes say that our narratives (made up of “choosing” important experiences from our lives) are in fact arguments. We use our narrative (aka the argument of our life) to justify ourselves against other people and the convictions they bring against our own. Our narratives are what ground us and give us stable footing to defend our existence when contrasting experiences come thundering upon us.

This now brings me to Sharon Roseman’s story.

Where am I?

In the episode of Radiolab titled “You Are Here,” Sharon is described as have DTD (Developmental Topographical Disorder), a condition which causes her world to rotate by 90 degrees. What Sharon once knew to be to in front of her would then be to the right of her. West would become North, and East would become South. Her whole world would rotate, rendering everything totally unfamiliar.

Though it wasn’t fully explored in this segment of Radiolab, I was curious about how Sharon’s condition affected her memories. I asked myself, if her world is constantly rotating without so much as a warning, then do her memories have the same consistency as ours? Is there a read thread that connects her experiences, tying them all into the same narrative, or do her memories live in two separate worlds? One where West is West, and the other where West is North.

If the second case is true, then this suggests that Sharon was not grounded! Her narrative would be in a state constant of disruption, proving a struggle to provide the evidence of herself and her convictions.

Being There

This connection of the formation of memories to Corder’s notions of narrative was what led me to discover the relationship between memories and their locations (which you read earlier on). Our memories are maps of our life experience; each individual memory being tied to a location, and all memories being mapped within the brain by a network of electrical signals.

So, dear readers, I advise you to become more attuned to your surroundings, because they’re more closely tied to your memories than you might think.