Introduction

Ever wonder how you’re brain is able to control the perception of time? At times it seems as if life is flying by – especially when we are involved in a fun activity or event. At other times, though, when we are stressed out or witness a scary event, time seems to stop or even freeze in our brains. Our perception of time is different from person to person, and definitely has a deep biological-rooted influence from within our brains.

Though we have things like watches and clocks to help us keep track of time, our brain is involved in the perception of how fast time passes. Like I’ve already mentioned, some people feel that one hour of listening to country music may go by extremely quick, while for others [that maybe aren’t interested in this genre] feel as if one hour was actually 3 or 4 hours. Being able to keep track of time is a skill that our brains’ have that allows us to determine what is happening in our surroundings and when to respond to that event.

Simple functions that we take for granted such as: hearing speech are even involved in our brain’s perception of time. As an example: we need to tell where a voice is coming from, how long the sound of it takes to reach our ears, etc. Also, when we respond to voices through the act of “talking,” we need to be timely with our responses.

Animals and studies of “time perception”

Researchers have found that telling time is even widely utilized by animals. University of Edinburgh researchers were able to study hummingbirds to determine how they told time. Researchers used fake flowers with sugar inside. They found that after hummingbirds drank the sweet nectar contained within real flowers, it took time for the flowers to replenish their nectar supply. The fake flowers were refilled every 10 minutes , while the real flowers were filled every 20 minutes. The hummingbirds were able to catch on to the time period it took for the nectar came back into both the real and the fake flowers.

Many other animals are also great time-tellers. Research on rats at the University of Georgia showed that rats do a phenomenal job at telling time. Rats can be taught to wait over 2 days after a meal to poke their noses through a trough and be given fresh food. Psychologists have hypothesized [for over 40 years] that both animals and human beings kept track of time with a biological version of a “stopwatch.” They strongly believed that within our brains, we had a “series of pulses” that were being generated. They thought that when our brains needed to “time an event,” a gate opened and those electrical pulsations turned into a “counting device.

The flawed brain-clock model of “time perception”

There was definitely good reasoning behind the brain-clock model of time perception. You’re time perception always will speed up when you are caught up in a pleasurable or fun event, while your brain will naturally slow down time perception when you are in a place you dislike or feel stressed out. These good and bad experiences were believed by psychologists to trigger the “pulsation generator” within our brains – thus speeding or slowing time depending on the given situation.

With that said, the biological roots within the brain don’t work like “clocks” that we understand. Neurons in our brain are able to produce steady pulses, however, our brain doesn’t have what it takes to count accurate pulses for even a few seconds. How we tell time is definitely far from the way a clock tells time. This is why scientists had to dismiss the brain-clock theory mentioned above.

Had our brains been built to work like that, we’d definitely be able to do a great job at estimating long periods of time better than short ones. Any individual or single pulses from the hypothetical clock within would be either a bit too slow, or a bit too fast. In short periods of time, the brain would begin to retain just a few short pulses, leaving plenty of room for error. The extra pulses that our brain would naturally error, would cancel themselves out [i.e. errors of telling time would be canceled out by the brain]. Though it sounds like it could be true, it’s not. Whenever we estimate longer periods of time, our errors don’t cancel themselves out – they keep accumulating.

What does our brain use to tell time?

At this day in age, tons of new breakthroughs and experiments are surfacing to help scientists better understand time within the brain. Things such as: studying genetically engineered mice, computer simulations in combination with E.E.G.’s, are being used to help scientists. The results of their studies prove that our brain doesn’t use any form of a “stopwatch.”

Our brains do not work like clocks or stopwatches that come to mind when we think of elapsed time. Instead, our brains utilize several other methods in order to tell time. Neuroscientist Dean Buonomano from U.C.L.A. believes that our brains tell time like they were observing “ripples in a pond.” He continues to argue that they perceive time in “fractions of seconds.” Let’s say you are listening to the sound of a summer cricket. The criket’s chirps are split by just one-tenth of a second. The cricket’s very first chirp immediately perks up our auditory neurons.

Sound signals are sensed by the neurons for less than half a second – same time as it takes ripples from a skimming a rock across the river to disappear. When the second cricket chirp is heard, the auditory neurons are still perked up. Therefore, the second chirp creates a different signal pattern. Dean Buonomano believes that our brains are able to compare the first pattern to the second patter in order to determine how much time has elapsed. Basically, the brain doesn’t contain an internal clock, because the telling of time is fixed in our neuronal behavior.

Dean Buonomano Theory vs. Warren Meck Theory

Should the U.C.L.A. researcher’s [Dean Buonomano] theory turn out to be correct, he will have explained only the “fast time telling” within the brain. Why? Because after half-of-a-second, the ripples in our brain clear out. On a bigger scale, which would range from a few seconds to a few hours, there must be a different way to study the brain’s time control processing.

That’s where Duke University’s Warren Meck comes into play. He has a different theory stating that: the brain measures long periods of time by producing pulses. However, he also believes that the brain doesn’t count the pulses like the way a “clock does.” He strongly believes that the brain listens to the pulses in the same way that our ears listen to music.

Warren Meck started developing his first “musical model” of time processing when he was studying the time perception of rodents; more specifically, the time perception of rats. All that Meck needed to do in order to kill their time processing was to destroy certain neuronal clusters within their brains. After taking a closer look at the situation, Meck found that some of these neurons differed from the rest of the neurons in the brain.

Each neuron was linked to a at least 20,000 other neurons in the brain. The “linked neurons” were able to be seen throughout the cortex. Many even linked to the outer parts of the brain which handle “sophisticated information processing.” While other neurons were linked to “controlling vision,” and even others worked to bind other areas into our perception. Because these neurons received many signals from “all over the brain,” he believes that these medium spiny neurons provide us with an accurate perception of time.

Picture yourself listening to a 30 second constant sound. At the beginning of listening to the constant sound, your neurons [found within your cortex] will reset themselves in order to fire in synchronized fashion. Some of the neurons fire faster than others, while others remain inactive. In between one split second and the next, the medium spiny neurons are able to read a unique pattern of signals from the many [20,000 +] interconnected neurons.

The pattern changes similar to pitch changes in between various notes of music. When the 30 seconds of the beat are up, the medium spiny neurons are able to “listen” to the “pitch changes” to determine the amount of elapsed time. Warren Meck has been able to provide evidence supporting his theory. How? Warren has recorded neuronal electrical activity and analyzed them deeply and has studied individuals with a “skewed sense of time.”

Healthy brains vs. Drugged brains & time perception

There are also specific neurotransmitters like dopamine which control the pulsing of neurons. Crystal meth and cocaine are examples of drugs that control the pulsing rate of neuron groups. They do this by overpowering the brain with abnormally high levels of dopamine. Several studies have proven the increased dopamine to have a profound effect on changing the perception of time.

In 2007, U.C.L.A. also ran an experiment. In the experiment, scientists rang a bell after 53 seconds of pure silence. Healthy individuals were told to guess how much time had passed. Most guessed an average of 67 seconds of time had elapsed. People on stimulants [which boost the amount of dopamine in the brain] guessed that an average of 91 seconds had passed. Many other drugs have the exact opposite effect on the amount of dopamine in the brain – thus compressing the subjective experience of time.

In even the most healthy brains, the processing of time varies. Staring at a scary face for 5 seconds feels significantly longer than staring at a neutral or happy one. It may not even be coincidence that pulse-generating neurons are embedded within regions of the brain that process emotionally-charged sounds and sights. Recently, researcher Amelia Hunt from Harvard University addressed the idea that every time we move our eyes, we may in fact be “pushing back our mental time.”

Amelia Hunt’s research at Harvard University

Even more recently, Amelia Hunt conducted an experiment where she had individuals stare “straight ahead” with a ticking clock off to one side of their gazes. Hunt then asked the individuals to move their eyes in order to see the clock. She told them to attempt to remember the time each time they had looked at the clock. On average, participants reported seeing the clock about four one-hundreths of a second before their eyes actually arrived at the clock.

The act of “pushing back” time may actually be a good thing, believes Hunt. It may allow us to cope with our slightly imperfect nervous systems. Every person has a highly-dense patch of light-sensitive cells in our retinas. These cells have been dubbed the name: fovea. We must move and jerk our eyes around several times in order for our fovea to generate an accurate, detailed image of our environment and surroundings; this gives the fovea enough time for scaling the features of our surroundings. The stream of signals from our eyes creates a series of jumps or bumps on the road. The human brain naturally will then allude us to believe that we are experiencing one complete “flow of reality.” When our brain realizes that it is still editing the “signaling jumps,” we may have errors in time perception.

Embedding time in our memories

However, the most shocking reworking of time may be the way it gets embedded in our memories. We usually always recall memories that include both: what happened, and when it happened. We understand how much time has passed since a certain past event by drumming up an event of the old memory. People who have brain damage as a result from injury or surgery – which depleted a certain part of the brain – gives researchers clues as to the way the brain embeds time within memories.

In 2007, scientists from France studied a group of individuals that were suffering from left-temporal lobe brain damage. The study participants then watched a film in which a familiar object appeared on the screen and reappeared a few minutes later [8 minutes later]. The study participants were then told to guess how much time had passed since first seeing the familiar object and seeing it for a second time. On average, the brain-damaged participants thought 8 minutes was really around 13 minutes. Healthy brain subjects were only off in guessing by roughly only one minute.

These type of experiments are great progress for researchers and scientists. They are slowly bridging the gap and honing in more on the regions of the brain which store memories of time. What is still unknown, is how these brain regions are able to record and understand time. Listening in on the brain’s signaling for a few minutes is one thing, but it is completely different [and much more complex] to understand how the brain’s neural networks of memories are able to deposit and withdraw [for later recollection] elapsed time during certain events.

Compressing memories of time [Berlin research]

It is interesting though, because scientists have by no means given up on understanding time-control in the brain. Researchers in Berlin, Germany have been working to build an accurate model of how memories may embed time. When neurons produce a normal generation of signals, some signals are received sooner – while others, a little later. These Berlin researchers believe that as the neurons communicate with one another, they pass the signals. While they are passing the signals, they can create slight adjustments [“wobbles”] – some bigger, some smaller. With these tiny “wobbles,” the brain is able to embed memories of time by compressing them. The brain is able to compress memories of several seconds down to “several hundreths” of a second. This allows the brain to save it’s space and easily have enough room to store many memories.

When your brain stores time in its memories, the brain is able to alter it in another significant way. Your brain could record the time such that we recall the events in a “backwards order.” M.I.T. researchers found that the brain was able to form reverse memories. They ran an experiment which included rats running down a track and stopping to eat food at the end of the track. When rats become more familiar with their environment, individual neurons became more active when they reached familiar spots.

Researchers discovered what are called “place cells.” These “place cells” fired off signals when rats moved to different places along the track. When the rats took a break and stopped to eat, researchers checked their brain activity again. They realized that the “place cells” fired again – due to the fact that memories of the track became stronger within their brains. However, the “place neurons” at the end of the track signaled first. The ones at the beginning of the track fired last. It is definitely possible, though, that we can reverse time processing in our memories in order to focus on our brains’ on something rewarding or a goal. Though we are not free from time, we are able to maintain some control over it. Our brains can bend it and twist it to properly fit our needs and reality.