"Time Cells" In the Brain Keep Track of Events, Firing As Time Goes By

By Rebecca Boyle Posted 08.25.2011 at 11:11 am 6 Comments

Time in a Nice Place Svadilfari via Flickr

Whether we’re engrossed in an activity or the alarm clock simply fails to chime, we’ve all been in situations when we say we’ve lost track of time. But our brains have not really lost track at all. A specific group of cells in the brain’s memory center is encoding for the passage of time, researchers report. These “time cells” are key to our perception of sequences of events.

In a new study involving rats, researchers at Boston University monitored neurons in the hippocampus, the center of memory and learning. Howard Eichenbaum and colleagues trained rats to perform a three-part task, which included a delay in the middle, reports ScienceNow. They learned to associate an object with an scent (a ball with oregano, for instance), and then they were presented with the object. The rats entered a separate chamber for 10 seconds, after which a doorway led them to a flowerpot full of scented sand. If the scent was the same as the object they’d been shown, the rats would dig for a food reward. The 10-second delay was at the heart of the study.

Eichenbaum et. al surgically implanted electrodes in the rats’ hippocampus, and monitored signals from 300 distinct neurons as the rats completed their work. During the delay, the researchers watched about a third of the cells continue to fire in a cascading pattern — suggesting the neurons were keeping track as time went by.

The hippocampus is known to have “place cells,” which keep track of locations and recalibrate when spatial cues are altered, the authors write. In the same way, the time neurons continued to fire when the researchers lengthened the delay, “retiming” when temporal cues are altered. The hippocampus is considered the brain’s memory center, so it makes sense that there would be some mechanism for monitoring the variables that memory depends upon.

The neurons kept track of time in varying tests, but their firing patterns and the specific groups involved changed slightly, depending on which object was presented. This shows the neurons disambiguate different events, the researchers say: “(They) compose unique, temporally organized representations of specific experiences.” The research is reported in the journal Neuron.

So next time you say you’ve lost track of time, remember that you really haven’t — your biological clock has been ticking all the while.

[via ScienceNow]

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6 Comments

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dkpopsci

08/25/11 at 11:28 am

Incredible.

____________________________________________________
My FYI Question :)

http://www.popsci.com/science/article/2010-10/fyi-what-would-happen-if-every-element-periodic-table-came-contact-simultaneously

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gizmowiz

08/25/11 at 11:46 am

Which makes perfect sense if you think about it. My mom has alzheimers and she cant keep track of time. as her memory gets worse so does her ability to keep time. she cant even now draw a clock and a month can go by without her knowing it

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BubbaGump

08/25/11 at 2:30 pm

I have read that in the calm before you sleep, if you tell yourself to wake at a specific time in the morning, you will by your own internal alarm clock. I have experimented with idea and feel it works.

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JediMindset

08/25/11 at 10:14 pm

so in a sense we could "stop" this clock to prevent aging. think about it, if we told our bodies that time doesn't matter we could live forever. if it keeps track of time than it has to know when to start to decay and get old. just something i thought up. maybe this "clock" is there to prevent overpopulation which could in someway be imprinted in our dna. just proves intelligent design even more.

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Onihikage

08/25/11 at 10:36 pm

@JediMindset: Not true, there are biological factors in aging as well as psychological ones, such as the caps on the ends of chromosomes, I forget the name but these shorten as we age, they act like a buffer for errors in cell division. The bigger they are, the longer you'll live (assuming some form of bodily harm doesn't do you in first).

Remember, this article is only talking about how our brains perceive the flow of time, i.e., from moment to moment, not its effects on us. Manipulating these neurons would probably only serve to make us remember sequences and timing of events differently. Imagine, in 100 years, dancers will flub their performances because of bio-hackers! (or perhaps they'll gain instant moves by pre-programming these neurons)

And while I believe in intelligent design, please leave it out of this discussion because this has nothing to do with that. It seems (if the study is correct) that this is simply the system which God gave us that helps us track and remember the passage of time. That's all there is to it. One with another ideology would say the same thing, just crediting a different source for the existence of this mechanism. Hence the ideologies are irrelevant in this piece of science.

It's cool to see more demonstration that neurons are multifunctional and specialized at the same time. (assuming the study is correct) We even have neurons that specifically track the passage of time and correlate it with memory. Amazing. :)

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JediMindset

08/26/11 at 6:08 pm

@Onihikage
could this be compared to how a tree grows rings on the trunk as it ages? but yeah i brought up intelligent design because we are the only species on Earth that tell others and teaches others about important events we experience. i believe that god is an alien and aliens are gods. modern religion is weak. the way i see it is love is the only religion we need. think about it, if its one thing all religions have in common and all religions preach is love.

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