We’ve all experienced the fluidity of time in one way or another. How a workday can feel like eternity, but the weekend flies by in a blink. The inconsistency we experience is largely due to how our brain perceives time and then translates it back to us.
The Brain’s Biological Clock
Before humans invented the clock, we relied on our biological clock to tell us when it was time to do something. This clock, or our circadian rhythm, is how our brain keeps track of the day between sunrise and sunset. Throughout the day, we get signals telling us to wake up, when we’re hungry, and when to go to sleep.
We still have this biological clock running, but our modern life often overrides it. We get up when our alarm clock demands instead of waking naturally in the morning. And then we’re inside for most of the day, making it difficult for our brain to determine if that blue light is coming from a screen or the sun.
So, we know that it isn’t our circadian rhythm dictating how we interpret time as much as it drives our body throughout the day. Tracking our needs isn’t really tracking time, at least, not in the way we’re used to understanding time. But it is a clue into how our brain sees time.
Encoding Time In Memory
Of course, the brain and time is a bit more complicated than simply when we wake up and when we go to sleep. We can usually remember when a memory takes place in relation to other memories, and we generally can track sequence in time. For example, we can remember if a vacation came before or after a promotion.
Typically, this is known as our episodic memory, and research has traced the presence of cells in our hippocampus as being active while we’re encoding these memories. These cells are known as the hippocampus time cells. They are located both in the hippocampus and the entorhinal cortex, and track the sequence of events with specific time stamps of ten-second durations.
It may seem like ten seconds isn’t a long time, but this short burst of time stamping is why we can remember events in a sort of movie-like way. It encodes them in these chunks in a similar way that movies are on individual frames. Isolated, they mark a single ten-second frame, but when we revisit the memory, they play back-to-back, giving us an incredibly vivid recollection.
This type of memory evolved not so we could remember birthday parties in detail, but so we could remember how to navigate trails seasonally or find the best hunting grounds. It helped establish dangerous events so we could avoid that, and allowed us to create story-telling so that each generation could build on each successive generation’s knowledge.
Interpreting Linear Time
At some point in our history, we developed the sense of time as a thing. In doing so, we created clocks to measure it and to also divide it into management increments. However, ask any quantum physicist, they’ll emphasize that time isn’t actually linear. It’s simply how we perceive it.
Building on the way our brain sequences memory in linear, episodic frames, it only made sense for us to physically represent time in a similar fashion. But there’s a reason time seems to go fast when we’re having a great time and drag forever when we’re not. And that’s thanks to time-sensitive neurons found in the supramarginal gyrus, also known as Brodmann area 40.
Brodmann area 40 is located in the right parietal cortex and is where we observe space and motion. These time-sensitive neurons activate in response to activity, but are only active for precise lengths of time. However, when we experience the same activity either for extended periods of time, or repeatedly, these neurons become less active and can stop entirely.
Essentially this means that in order to encode a time-stamped memory, we also need time-sensitive neurons to activate. And they are really active when we’re doing new things, or things that interest us. But when it comes to the more mundane parts of life, like waiting in line at the DMV, these neurons become inactive and our sense of time slows down.
Without specific events to help our brain mark the passage of time, it struggles to interpret time. This is why when we do the same thing every day, it can become difficult to remember what day it is, or when we completed a repetitive task. It all blurs without the time-sensitive neuronal activity. These neurons can also become more difficult to activate when we’re tired, which is why the day can feel excessively long if we aren’t feeling well rested.
There’s no disputing that time exists. We age and experience events over the course of our lifetimes. But the way we perceive that time is in large part due to the way the neurons in our brain interpret events and encode our memories.
Time in essence is our memory, moving from event to event, and as we remember these events, our brain sees the time that has passed. In order to help experience time in a more consistent fashion, find ways to add novelty to mundane activities and break up repetitive tasks whenever possible. Not only will this help improve memory, it will make the experience of time richer and more consistent as well.